[Tarantool-patches] [PATCH v17 0/2] box: implement cmod Lua module

[Tarantool-patches] [PATCH v17 0/2] box: implement cmod Lua module

[Cyrill Gorcunov via Tarantool-patches]

Please take a look once time permit.

v1-v3 are development ones and not sent.

v5 (by vlad):
 - drop exists, list methods: they are redundant
 - rename cfunc to cbox
 - when create a function make it callable Lua object
 - initialize cbox out of modules
 - fix error in passing module name for reloading
 - make api been cbox.func.[create|drop] and
   cbox.module.reload
 - fix test for OSX sake

v6 (by vlad):
 - move module handling into module_cache file.
v7:
 - development
v8:
 - use rbtree for function instance storage, since
   i don't like the idea of unexpected rehashing of
   values in case of massive number of functions
   allocated
 - use reference counter and free function instance
   if only load/unload are coupled
 - keep a pointer to the function inside Lua object
   so we don't need to lookup on every function call.
   this force us to implement __gc method
 - use new API and update docs
v9:
 - development
v10:
 - use hashes for function names lookup
 - simply function loads counting
 - use luaL_register_module and luaL_register_type for
   easier methods registering
 - carry functions as userdata object
v11:
 - development
v12:
 - switch to new API as been discussed in
   https://lists.tarantool.org/tarantool-patches/e186c454-6765-4776-6433-f3f791ff4c27@tarantool.org/
v13:
 - development
v14:
 - switch to refs to carry module usage
 - drop func_name structure renaming
 - carry two hashes for backward compatibility with
   functions created via box.schema.func help
 - complete rework of cmod and most parts of
   module_cache
 - account for file statistics to invalidate
   module cache
 - new API for cmod, no more :reload, the :load
   procedure uses cache invalidation
 - update test cases
 - still there is no GC test since I didn't
   manage to deal with it
v15:
 - report module state cached/orphan
 - update test cases
 - do not prevent functions lookup in orphan modules
 - there was an idea to use box.shema.func cache as on
   top of cmod's one, but this doesn't work because in case
   if module doesnt exist in any caches we would put it into
   into cmod's one as well but there wont be a module on
   cmod level which would clean it up later (which makes
   code a way more comple if we choose to track state
   of modules).
v16:
 - internal
v17:
 - drop idea of unifying box.schema.func and cmod functions
   cache, it brings more problems than solves due to too
   different context of execution;
 - make cmod self consistent, which shrink patch series
   size ~1/5 in compare with previous attempts;
 - improve tests to account internal states of modules
   and functions (tt_dev key in reports).

branch gorcunov/gh-4642-func-ro-17
issue https://github.com/tarantool/tarantool/issues/4642

Cyrill Gorcunov (2):
  box/cmod: implement cmod Lua module
  test: box/cfunc -- add cmod test

 src/box/CMakeLists.txt  |   1 +
 src/box/lua/cmod.c      | 959 ++++++++++++++++++++++++++++++++++++++++
 src/box/lua/cmod.h      |  25 ++
 src/box/lua/init.c      |   2 +
 test/box/CMakeLists.txt |   2 +
 test/box/cfunc1.c       |  58 +++
 test/box/cfunc2.c       | 137 ++++++
 test/box/cmod.result    | 418 +++++++++++++++++
 test/box/cmod.test.lua  | 155 +++++++
 test/box/suite.ini      |   2 +-
 10 files changed, 1758 insertions(+), 1 deletion(-)
 create mode 100644 src/box/lua/cmod.c
 create mode 100644 src/box/lua/cmod.h
 create mode 100644 test/box/cfunc1.c
 create mode 100644 test/box/cfunc2.c
 create mode 100644 test/box/cmod.result
 create mode 100644 test/box/cmod.test.lua


base-commit: 1a01c906fe5f337dae0cf2f21738312c3a8a4c61
-- 
2.29.2

[Tarantool-patches] [PATCH v17 1/2] box/cmod: implement cmod Lua module

[Cyrill Gorcunov via Tarantool-patches]

Currently to run "C" function from some external module one
have to register it first in "_func" system space. This is
a problem if node is in read-only mode (replica).

Still people would like to have a way to run such functions
even in ro mode. For this sake we implement "cmod" lua module.

Unlike `box.schema.func` interface the cmod does not defer module
loading procedure until first call of a function. Instead a module
is loaded immediately and if some error happens (say shared
library is corrupted or not found) it pops up early.

The need of use stored C procedures implies that application is
running under serious loads most likely there is modular structure
present on Lua level (ie same shared library is loaded in different
sources) thus we cache the loaded library and reuse it on next
load attempts. To verify that cached library is up to day we
test for file attributes (device, inode, size, modification time)
on every load attempt.

Closes #4642

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>

@TarantoolBot document
Title: cmod module

Overview
========

`cmod` module provides a way to create, delete and execute
`C` procedures from shared libraries. Unlike `box.schema.func`
methods the functions created with `cmod` help are not persistent
and live purely in memory. Once a node get turned off they are
vanished. An initial purpose for them is to execute them on
nodes which are running in read-only mode.

Module functions
================

`require('cmod').load(path) -> obj | error`
-------------------------------------------

Loads a module from `path` and return an object instance
associate with the module, otherwise an error is thrown.

The `path` should not end up with shared library extension
(such as `.so`), only a file name shall be there.

Possible errors:

- IllegalParams: module path is either not supplied
  or not a string.
- SystemError: unable to open a module due to a system error.
- ClientError: a module does not exist.
- OutOfMemory: unable to allocate a module.

Example:

``` Lua
-- Without error handling
m = require('cmod').load('path/to/library)

-- With error handling
m, err = pcall(require('cmod').load, 'path/to/library')
if err ~= nil then
    print(err)
end
```

`module:unload() -> true | error`
---------------------------------

Unloads a module. Returns `true` on success, otherwise an error
is thrown. Once the module is unloaded one can't load new
functions from this module instance.

Possible errors:

- IllegalParams: a module is not supplied.
- IllegalParams: a module is already unloaded.

Example:

``` Lua
m = require('cmod').load('path/to/library')
--
-- do something with module
--
m:unload()
```

If there are functions from this module referenced somewhere
in other places of Lua code they still can be executed because
the module continue sitting in memory until the last reference
to it is closed.

If the module become a target to the Lua's garbage collector
then unload is called implicitly.

module:load(name) -> obj | error`
---------------------------------

Loads a new function with name `name` from the previously
loaded `module` and return a callable object instance
associated with the function. On failure an error is thrown.

Possible errors:
 - IllegalParams: function name is either not supplied
   or not a string.
 - IllegalParams: attempt to load a function but module
   has been unloaded already.
 - ClientError: no such function in the module.
 - OutOfMemory: unable to allocate a function.

Example:

``` Lua
-- Load a module if not been loaded yet.
m = require('cmod').load('path/to/library')
-- Load a function with the `foo` name from the module `m`.
func = m:load('foo')
```

In case if there is no need for further loading of other
functions from the same module then the module might be
unloaded immediately.

``` Lua
m = require('cmod').load('path/to/library')
func = m:load('foo')
m:unload()
```

`function:unload() -> true | error`
-----------------------------------

Unloads a function. Returns `true` on success, otherwise
an error is thrown.

Possible errors:
 - IllegalParams: function name is either not supplied
   or not a string.
 - IllegalParams: the function already unloaded.

Example:

``` Lua
m = require('cmod').load('path/to/library')
func = m:load('foo')
--
-- do something with function and cleanup then
--
func:unload()
m:unload()
```

If the function become a target to the Lua's garbage collector
then unload is called implicitly.

Executing a loaded function
===========================

Once function is loaded it can be executed as an ordinary Lua call.
Lets consider the following example. We have a `C` function which
takes two numbers and returns their sum.

``` C
int
cfunc_sum(box_function_ctx_t *ctx, const char *args, const char *args_end)
{
	uint32_t arg_count = mp_decode_array(&args);
	if (arg_count != 2) {
		return box_error_set(__FILE__, __LINE__, ER_PROC_C, "%s",
				     "invalid argument count");
	}
	uint64_t a = mp_decode_uint(&args);
	uint64_t b = mp_decode_uint(&args);

	char res[16];
	char *end = mp_encode_uint(res, a + b);
	box_return_mp(ctx, res, end);
	return 0;
}
```

The name of the function is `cfunc_sum` and the function is built into
`cfunc.so` shared library.

First we should load it as

``` Lua
m = require('cmod').load('cfunc')
cfunc_sum = m:load('cfunc_sum')
```

Once successfully loaded we can execute it. Note that unlike regular
Lua functions the context of `C` functions is different. They never
thrown an exception but return `true|nil, res` form where first value
set to `nil` in case of error condition and `res` carries an error
description.

Lets call the `cfunc_sum` with wrong number of arguments

``` Lua
cfunc_sum()
 | ---
 | - error: invalid argument count
```

We will see the `"invalid argument count"` message in output.
The error message has been set by the `box_error_set` in `C`
code above.

On success the sum of arguments will be printed out.

``` Lua
cfunc_sum(1, 2)
 | ---
 | - 3
```

The functions may return multiple results. For example a trivial
echo function which prints arguments passed in.

``` Lua
cfunc_echo(1,2,3)
 | ---
 | - 1
 | - 2
 | - 3
```

Module and function caches
==========================

Loading a module is relatively slow procedure because operating
system needs to read the library, resolve its symbols and etc.
Thus to speedup this procedure if the module is loaded for a first
time we put it into an internal cache. If module is sitting in
the cache already and new request to load comes in -- we simply
reuse a previous copy. In case if module is updated on a storage
device then on new load attempt we detect that file attributes
(such as device number, inode, size, modification time) get changed
and reload module from the scratch. Note that newly loaded module
does not intersect with previously loaded modules, the continue
operating with code previously read from cache.

Thus if there is a need to update a module then all module instances
should be unloaded (together with functions) and loaded again.

Similar caching technique applied to functions -- only first function
allocation cause symbol resolving, next ones are simply obtained from
a function cache.
---
 src/box/CMakeLists.txt |   1 +
 src/box/lua/cmod.c     | 959 +++++++++++++++++++++++++++++++++++++++++
 src/box/lua/cmod.h     |  25 ++
 src/box/lua/init.c     |   2 +
 4 files changed, 987 insertions(+)
 create mode 100644 src/box/lua/cmod.c
 create mode 100644 src/box/lua/cmod.h

diff --git a/src/box/CMakeLists.txt b/src/box/CMakeLists.txt
index 19203f770..fa4253c5d 100644
--- a/src/box/CMakeLists.txt
+++ b/src/box/CMakeLists.txt
@@ -195,6 +195,7 @@ add_library(box STATIC
     lua/call.c
     lua/cfg.cc
     lua/console.c
+    lua/cmod.c
     lua/serialize_lua.c
     lua/tuple.c
     lua/slab.c
diff --git a/src/box/lua/cmod.c b/src/box/lua/cmod.c
new file mode 100644
index 000000000..b55572b6d
--- /dev/null
+++ b/src/box/lua/cmod.c
@@ -0,0 +1,959 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright 2010-2021, Tarantool AUTHORS, please see AUTHORS file.
+ */
+
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#include <unistd.h>
+#include <string.h>
+#include <dlfcn.h>
+#include <fcntl.h>
+#include <lua.h>
+
+#include "box/error.h"
+#include "box/port.h"
+#include "box/func_def.h"
+
+#include "tt_static.h"
+
+#include "fiber.h"
+#include "assoc.h"
+
+#include "trivia/config.h"
+
+#include "lua/utils.h"
+#include "libeio/eio.h"
+
+/**
+ * Attributes for cmod cache invalidation.
+ */
+struct cmod_attr {
+#ifdef TARGET_OS_DARWIN
+	struct timespec st_mtimespec;
+#else
+	struct timespec st_mtim;
+#endif
+	dev_t st_dev;
+	ino_t st_ino;
+	off_t st_size;
+};
+
+/**
+ * Shared library module.
+ */
+struct cmod {
+	/** Module dlhandle. */
+	void *handle;
+	/** Module ID. */
+	int64_t id;
+	/** Number of references. */
+	int64_t refs;
+	/** File attributes. */
+	struct cmod_attr attr;
+	/** Length of @a package. */
+	size_t package_len;
+	/** Path to the module. */
+	char package[0];
+};
+
+/**
+ * Function descriptor.
+ */
+struct cmod_func {
+	/** Module function belongs to. */
+	struct cmod *cmod;
+	/** Address to execute on call. */
+	box_function_f addr;
+	/** Number of references. */
+	int64_t refs;
+	/** Length of functon name in @a key. */
+	size_t sym_len;
+	/** Length of @a key. */
+	size_t len;
+	/** Function hash key. */
+	char key[0];
+};
+
+/** Module name to cmod hash. */
+static struct mh_strnptr_t *cmod_hash = NULL;
+
+/** Function name to cmod_func hash. */
+static struct mh_strnptr_t *cmod_func_hash = NULL;
+
+/** A type to find a module from an object. */
+static const char *uname_cmod = "tt_uname_cmod";
+
+/** A type to find a function from an object. */
+static const char *uname_func = "tt_uname_cmod_func";
+
+/** Module unique IDs. */
+static int64_t cmod_ids = 1;
+
+/** Get data associated with an object. */
+static void *
+get_udata(struct lua_State *L, const char *uname)
+{
+	void **pptr = luaL_testudata(L, 1, uname);
+	return pptr != NULL ? *pptr : NULL;
+}
+
+/** Set data to a new value. */
+static void
+set_udata(struct lua_State *L, const char *uname, void *ptr)
+{
+	void **pptr = luaL_testudata(L, 1, uname);
+	assert(pptr != NULL);
+	*pptr = ptr;
+}
+
+/** Setup a new data and associate it with an object. */
+static void
+new_udata(struct lua_State *L, const char *uname, void *ptr)
+{
+	*(void **)lua_newuserdata(L, sizeof(void *)) = ptr;
+	luaL_getmetatable(L, uname);
+	lua_setmetatable(L, -2);
+}
+
+/**
+ * Helpers for string based hash manipulations.
+ */
+static void *
+hash_find(struct mh_strnptr_t *h, const char *str, size_t len)
+{
+	mh_int_t e = mh_strnptr_find_inp(h, str, len);
+	if (e == mh_end(h))
+		return NULL;
+	return mh_strnptr_node(h, e)->val;
+}
+
+static void
+hash_update(struct mh_strnptr_t *h, const char *src_str, size_t len,
+	    const char *new_str, void *new_val)
+{
+	mh_int_t e = mh_strnptr_find_inp(h, src_str, len);
+	if (e == mh_end(h))
+		panic("cmod: failed to update hash");
+	mh_strnptr_node(h, e)->str = new_str;
+	mh_strnptr_node(h, e)->val = new_val;
+}
+
+static int
+hash_add(struct mh_strnptr_t *h, const char *str, size_t len, void *val)
+{
+	const struct mh_strnptr_node_t nd = {
+		.str	= str,
+		.len	= len,
+		.hash	= mh_strn_hash(str, len),
+		.val	= val,
+	};
+	if (mh_strnptr_put(h, &nd, NULL, NULL) == mh_end(h)) {
+		diag_set(OutOfMemory, sizeof(nd), "malloc",
+			 "cmod: hash node");
+		return -1;
+	}
+	return 0;
+}
+
+static void
+hash_del_kv(struct mh_strnptr_t *h, const char *str,
+	    size_t len, void *val)
+{
+	mh_int_t e = mh_strnptr_find_inp(h, str, len);
+	if (e != mh_end(h)) {
+		void *v = mh_strnptr_node(h, e)->val;
+		if (v == val)
+			mh_strnptr_del(h, e, NULL);
+	}
+}
+
+static void
+hash_del(struct mh_strnptr_t *h, const char *str, size_t len)
+{
+	mh_int_t e = mh_strnptr_find_inp(h, str, len);
+	if (e != mh_end(h))
+		mh_strnptr_del(h, e, NULL);
+}
+
+/** Arguments for lpackage_search. */
+struct find_ctx {
+	const char *package;
+	size_t package_len;
+	char *path;
+	size_t path_len;
+};
+
+/** A cpcall() helper for lfind_package(). */
+static int
+lpackage_search(lua_State *L)
+{
+	struct find_ctx *ctx = (void *)lua_topointer(L, 1);
+
+	lua_getglobal(L, "package");
+	lua_getfield(L, -1, "search");
+	lua_pushlstring(L, ctx->package, ctx->package_len);
+
+	lua_call(L, 1, 1);
+	if (lua_isnil(L, -1))
+		return luaL_error(L, "cmod: module not found");
+
+	char resolved[PATH_MAX];
+	if (realpath(lua_tostring(L, -1), resolved) == NULL) {
+		diag_set(SystemError, "cmod: realpath");
+		return luaT_error(L);
+	}
+
+	/*
+	 * No need for result being trimmed test, it
+	 * is guaranteed by realpath call.
+	 */
+	snprintf(ctx->path, ctx->path_len, "%s", resolved);
+	return 0;
+}
+
+/** Find path to a module using Lua's package.cpath. */
+static int
+lfind_package(const char *package, size_t package_len,
+	      char *path, size_t path_len)
+{
+	struct find_ctx ctx = {
+		.package	= package,
+		.package_len	= package_len,
+		.path		= path,
+		.path_len	= path_len,
+	};
+
+	lua_State *L = tarantool_L;
+	int top = lua_gettop(L);
+	if (luaT_cpcall(L, lpackage_search, &ctx) != 0) {
+		diag_set(ClientError, ER_LOAD_MODULE, ctx.package_len,
+			 ctx.package, lua_tostring(L, -1));
+		lua_settop(L, top);
+		return -1;
+	}
+	assert(top == lua_gettop(L));
+	return 0;
+}
+
+/** Increase reference to cmod. */
+static void
+cmod_ref(struct cmod *m)
+{
+	assert(m->refs >= 0);
+	m->refs++;
+}
+
+/** Decrease reference to cmod and free it if last one. */
+static void
+cmod_unref(struct cmod *m)
+{
+	assert(m->refs > 0);
+	if (m->refs-- == 1) {
+		hash_del_kv(cmod_hash, m->package, m->package_len, m);
+		dlclose(m->handle);
+		TRASH(m);
+		free(m);
+	}
+}
+
+/** Fill cmod attributes from stat. */
+static void
+cmod_attr_fill(struct cmod_attr *attr, struct stat *st)
+{
+	attr->st_dev = st->st_dev;
+	attr->st_ino = st->st_ino;
+	attr->st_size = st->st_size;
+#ifdef TARGET_OS_DARWIN
+	attr->st_mtimespec = st->st_mtimespec;
+#else
+	attr->st_mtim = st->st_mtim;
+#endif
+}
+
+/**
+ * Allocate and load a new C module instance.
+ *
+ * Allocates a new C module instance, copies shared library
+ * to a safe place, loads it and remove then leaving DSO purely
+ * in memory. This is done because libc doesn't detect file
+ * updates properly. The module get cached by putting it into
+ * the modules hash.
+ *
+ * @param package package name.
+ * @param package_len length of @a package.
+ * @param source_path path to the shared library.
+ *
+ * @returns module pointer on succes, NULL otherwise, diag is set.
+ */
+static struct cmod *
+cmod_new(const char *package, size_t package_len, const char *source_path)
+{
+	size_t size = sizeof(struct cmod) + package_len + 1;
+	struct cmod *m = malloc(size);
+	if (m == NULL) {
+		diag_set(OutOfMemory, size, "malloc", "cmod");
+		return NULL;
+	}
+
+	m->package_len = package_len;
+	m->refs = 0;
+
+	memcpy(m->package, package, package_len);
+	m->package[package_len] = 0;
+
+	const char *tmpdir = getenv("TMPDIR");
+	if (tmpdir == NULL)
+		tmpdir = "/tmp";
+
+	char dir_name[PATH_MAX];
+	int rc = snprintf(dir_name, sizeof(dir_name),
+			  "%s/tntXXXXXX", tmpdir);
+	if (rc < 0 || (size_t)rc >= sizeof(dir_name)) {
+		diag_set(SystemError, "failed to generate path to tmp dir");
+		goto error;
+	}
+
+	if (mkdtemp(dir_name) == NULL) {
+		diag_set(SystemError, "failed to create unique dir name %s",
+			 dir_name);
+		goto error;
+	}
+
+	char load_name[PATH_MAX];
+	rc = snprintf(load_name, sizeof(load_name),
+		      "%s/%.*s." TARANTOOL_LIBEXT,
+		      dir_name, (int)package_len, package);
+	if (rc < 0 || (size_t)rc >= sizeof(dir_name)) {
+		diag_set(SystemError, "failed to generate path to DSO");
+		goto error;
+	}
+
+	struct stat st;
+	if (stat(source_path, &st) < 0) {
+		diag_set(SystemError, "failed to stat() module %s",
+			 source_path);
+		goto error;
+	}
+	cmod_attr_fill(&m->attr, &st);
+
+	int source_fd = open(source_path, O_RDONLY);
+	if (source_fd < 0) {
+		diag_set(SystemError, "failed to open module %s "
+			 "file for reading", source_path);
+		goto error;
+	}
+	int dest_fd = open(load_name, O_WRONLY | O_CREAT | O_TRUNC,
+			   st.st_mode & 0777);
+	if (dest_fd < 0) {
+		diag_set(SystemError, "failed to open file %s "
+			 "for writing ", load_name);
+		close(source_fd);
+		goto error;
+	}
+
+	off_t ret = eio_sendfile_sync(dest_fd, source_fd, 0, st.st_size);
+	close(source_fd);
+	close(dest_fd);
+	if (ret != st.st_size) {
+		diag_set(SystemError, "failed to copy DSO %s to %s",
+			 source_path, load_name);
+		goto error;
+	}
+
+	m->handle = dlopen(load_name, RTLD_NOW | RTLD_LOCAL);
+	if (unlink(load_name) != 0)
+		say_warn("failed to unlink dso link %s", load_name);
+	if (rmdir(dir_name) != 0)
+		say_warn("failed to delete temporary dir %s", dir_name);
+	if (m->handle == NULL) {
+		diag_set(ClientError, ER_LOAD_MODULE, package_len,
+			  package, dlerror());
+		goto error;
+	}
+
+	m->id = cmod_ids++;
+	cmod_ref(m);
+	return m;
+
+error:
+	free(m);
+	return NULL;
+}
+
+/**
+ * Load a module.
+ *
+ * This function takes a module path from the caller
+ * stack @a L and returns cached module instance or
+ * creates a new module object.
+ *
+ * Possible errors:
+ *
+ * - IllegalParams: module path is either not supplied
+ *   or not a string.
+ * - SystemError: unable to open a module due to a system error.
+ * - ClientError: a module does not exist.
+ * - OutOfMemory: unable to allocate a module.
+ *
+ * @returns module object on success or throws an error.
+ */
+static int
+lcmod_load(struct lua_State *L)
+{
+	const char msg_noname[] = "Expects cmod.load(\'name\') "
+		"but no name passed";
+
+	if (lua_gettop(L) != 1 || !lua_isstring(L, 1)) {
+		diag_set(IllegalParams, msg_noname);
+		return luaT_error(L);
+	}
+
+	size_t name_len;
+	const char *name = lua_tolstring(L, 1, &name_len);
+
+	if (name_len < 1) {
+		diag_set(IllegalParams, msg_noname);
+		return luaT_error(L);
+	}
+
+	char path[PATH_MAX];
+	if (lfind_package(name, name_len, path, sizeof(path)) != 0)
+		return luaT_error(L);
+
+	struct cmod *m = hash_find(cmod_hash, name, name_len);
+	if (m != NULL) {
+		struct cmod_attr attr;
+		struct stat st;
+		if (stat(path, &st) != 0) {
+			diag_set(SystemError, "failed to stat() %s",
+				 path);
+			return luaT_error(L);
+		}
+
+		/*
+		 * In case of cache hit we may reuse existing
+		 * module which speedup load procedure.
+		 */
+		cmod_attr_fill(&attr, &st);
+		if (memcmp(&attr, &m->attr, sizeof(attr)) == 0) {
+			cmod_ref(m);
+			new_udata(L, uname_cmod, m);
+			return 1;
+		}
+
+		/*
+		 * Module has been updated on a storage device,
+		 * so load a new instance and update the cache,
+		 * old entry get evicted but continue residing
+		 * in memory, fully functional, until last
+		 * function is unloaded.
+		 */
+		m = cmod_new(name, name_len, path);
+		if (m == NULL)
+			return luaT_error(L);
+
+		hash_update(cmod_hash, name, name_len, m->package, m);
+	} else {
+		m = cmod_new(name, name_len, path);
+		if (m == NULL)
+			return luaT_error(L);
+		if (hash_add(cmod_hash, m->package, name_len, m) != 0) {
+			/* Never been in hash: safe for hash_del_kv */
+			cmod_unref(m);
+			return luaT_error(L);
+		}
+	}
+
+	new_udata(L, uname_cmod, m);
+	return 1;
+}
+
+/**
+ * Unload a module.
+ *
+ * Take a module object from the caller stack @a L and unload it.
+ *
+ * Possible errors:
+ *
+ * - IllegalParams: module is not supplied.
+ * - IllegalParams: the module is unloaded.
+ *
+ * @returns true on success or throwns an error.
+ */
+static int
+lcmod_unload(struct lua_State *L)
+{
+	if (lua_gettop(L) != 1) {
+		diag_set(IllegalParams, "Expects module:unload()");
+		return luaT_error(L);
+	}
+
+	struct cmod *m = get_udata(L, uname_cmod);
+	if (m == NULL) {
+		diag_set(IllegalParams, "The module is unloaded");
+		return luaT_error(L);
+	}
+
+	set_udata(L, uname_cmod, NULL);
+	cmod_unref(m);
+	lua_pushboolean(L, true);
+	return 1;
+}
+
+/** Handle __index request for a module object. */
+static int
+lcmod_index(struct lua_State *L)
+{
+	lua_getmetatable(L, 1);
+	lua_pushvalue(L, 2);
+	lua_rawget(L, -2);
+	if (!lua_isnil(L, -1))
+		return 1;
+
+	struct cmod *m = get_udata(L, uname_cmod);
+	if (m == NULL) {
+		lua_pushnil(L);
+		return 1;
+	}
+
+	const char *key = lua_tostring(L, 2);
+	if (key == NULL || lua_type(L, 2) != LUA_TSTRING) {
+		diag_set(IllegalParams,
+			 "Bad params, use __index(obj, <string>)");
+		return luaT_error(L);
+	}
+
+	if (strcmp(key, "path") == 0) {
+		lua_pushstring(L, m->package);
+		return 1;
+	}
+
+	/*
+	 * Internal keys for debug only, not API.
+	 */
+	if (strncmp(key, "tt_dev.", 7) == 0) {
+		const char *subkey = &key[7];
+		if (strcmp(subkey, "refs") == 0) {
+			lua_pushnumber(L, m->refs);
+			return 1;
+		} else if (strcmp(subkey, "id") == 0) {
+			lua_pushnumber(L, m->id);
+			return 1;
+		}
+	}
+	return 0;
+}
+
+/** Module representation for REPL (console). */
+static int
+lcmod_serialize(struct lua_State *L)
+{
+	struct cmod *m = get_udata(L, uname_cmod);
+	if (m == NULL) {
+		lua_pushnil(L);
+		return 1;
+	}
+
+	lua_createtable(L, 0, 1);
+	lua_pushstring(L, m->package);
+	lua_setfield(L, -2, "path");
+	return 1;
+}
+
+/** Collect a module. */
+static int
+lcmod_gc(struct lua_State *L)
+{
+	struct cmod *m = get_udata(L, uname_cmod);
+	if (m != NULL) {
+		set_udata(L, uname_cmod, NULL);
+		cmod_unref(m);
+	}
+	return 0;
+}
+
+/** Increase reference to a function. */
+static void
+cmod_func_ref(struct cmod_func *cf)
+{
+	assert(cf->refs >= 0);
+	cf->refs++;
+}
+
+/** Free function memory. */
+static void
+cmod_func_delete(struct cmod_func *cf)
+{
+	TRASH(cf);
+	free(cf);
+}
+
+/** Unreference a function and free if last one. */
+static void
+cmod_func_unref(struct cmod_func *cf)
+{
+	assert(cf->refs > 0);
+	if (cf->refs-- == 1) {
+		cmod_unref(cf->cmod);
+		hash_del(cmod_func_hash, cf->key, cf->len);
+		cmod_func_delete(cf);
+	}
+}
+
+/** Function name from a hash key. */
+static char *
+cmod_func_sym(struct cmod_func *cf)
+{
+	return &cf->key[cf->len - cf->sym_len];
+}
+
+/**
+ * Allocate a new function instance and resolve its address.
+ *
+ * @param m a module the function should be loaded from.
+ * @param key function hash key, ie "1.module.foo".
+ * @param len length of @a key.
+ * @param sym_len function symbol name length, ie 3 for "foo".
+ *
+ * @returns function instance on success, NULL otherwise (diag is set).
+ */
+static struct cmod_func *
+cmod_func_new(struct cmod *m, const char *key, size_t len, size_t sym_len)
+{
+	size_t size = sizeof(struct cmod_func) + len + 1;
+	struct cmod_func *cf = malloc(size);
+	if (cf == NULL) {
+		diag_set(OutOfMemory, size, "malloc", "cf");
+		return NULL;
+	}
+
+	cf->cmod = m;
+	cf->len = len;
+	cf->sym_len = sym_len;
+	cf->refs = 0;
+
+	memcpy(cf->key, key, len);
+	cf->key[len] = '\0';
+
+	cf->addr = dlsym(m->handle, cmod_func_sym(cf));
+	if (cf->addr == NULL) {
+		diag_set(ClientError, ER_LOAD_FUNCTION,
+			 cmod_func_sym(cf), dlerror());
+		cmod_func_delete(cf);
+		return NULL;
+	}
+
+	if (hash_add(cmod_func_hash, cf->key, cf->len, cf) != 0) {
+		cmod_func_delete(cf);
+		return NULL;
+	}
+
+	/*
+	 * Each new function depends on module presence.
+	 * Module will reside even if been unload
+	 * explicitly after the function creation.
+	 */
+	cmod_ref(cf->cmod);
+	cmod_func_ref(cf);
+	return cf;
+}
+
+/**
+ * Load a function.
+ *
+ * This function takes a function name from the caller
+ * stack @a L and either returns a cached function or
+ * creates a new function object.
+ *
+ * Possible errors:
+ *
+ * - IllegalParams: function name is either not supplied
+ *   or not a string.
+ * - SystemError: unable to open a module due to a system error.
+ * - ClientError: a module does not exist.
+ * - OutOfMemory: unable to allocate a module.
+ *
+ * @returns module object on success or throws an error.
+ */
+static int
+lcmod_load_func(struct lua_State *L)
+{
+	const char *method = "function = module:load";
+	const char fmt_noname[] = "Expects %s(\'name\') but no name passed";
+
+	if (lua_gettop(L) != 2 || !lua_isstring(L, 2)) {
+		diag_set(IllegalParams, fmt_noname, method);
+		return luaT_error(L);
+	}
+
+	struct cmod *m = get_udata(L, uname_cmod);
+	if (m == NULL) {
+		const char *fmt =
+			"Expects %s(\'name\') but not module object passed";
+		diag_set(IllegalParams, fmt, method);
+		return luaT_error(L);
+	}
+
+	size_t sym_len;
+	const char *sym = lua_tolstring(L, 2, &sym_len);
+
+	if (sym_len < 1) {
+		diag_set(IllegalParams, fmt_noname, method);
+		return luaT_error(L);
+	}
+
+	/*
+	 * Functions are bound to a module symbols, thus
+	 * since the hash is global it should be unique
+	 * per module. The symbol (function name) is the
+	 * last part of the hash key.
+	 */
+	const char *key = tt_sprintf("%lld.%s.%s", (long long)m->id,
+				     m->package, sym);
+	size_t len = strlen(key);
+
+	struct cmod_func *cf = hash_find(cmod_func_hash, key, len);
+	if (cf == NULL) {
+		cf = cmod_func_new(m, key, len, sym_len);
+		if (cf == NULL)
+			return luaT_error(L);
+	} else {
+		cmod_func_ref(cf);
+	}
+
+	new_udata(L, uname_func, cf);
+	return 1;
+}
+
+/**
+ * Unload a function.
+ *
+ * Take a function object from the caller stack @a L and unload it.
+ *
+ * Possible errors:
+ *
+ * - IllegalParams: the function is not supplied.
+ * - IllegalParams: the function already unloaded.
+ *
+ * @returns true on success or throwns an error.
+ */
+static int
+lfunc_unload(struct lua_State *L)
+{
+	if (lua_gettop(L) != 1) {
+		diag_set(IllegalParams, "Expects function:unload()");
+		return luaT_error(L);
+	}
+
+	struct cmod_func *cf = get_udata(L, uname_func);
+	if (cf == NULL) {
+		diag_set(IllegalParams, "The function is unloaded");
+		return luaT_error(L);
+	}
+
+	set_udata(L, uname_func, NULL);
+	cmod_func_unref(cf);
+
+	lua_pushboolean(L, true);
+	return 1;
+}
+
+/** Handle __index request for a function object. */
+static int
+lfunc_index(struct lua_State *L)
+{
+	lua_getmetatable(L, 1);
+	lua_pushvalue(L, 2);
+	lua_rawget(L, -2);
+	if (!lua_isnil(L, -1))
+		return 1;
+
+	struct cmod_func *cf = get_udata(L, uname_func);
+	if (cf == NULL) {
+		lua_pushnil(L);
+		return 1;
+	}
+
+	const char *key = lua_tostring(L, 2);
+	if (key == NULL || lua_type(L, 2) != LUA_TSTRING) {
+		diag_set(IllegalParams,
+			 "Bad params, use __index(obj, <string>)");
+		return luaT_error(L);
+	}
+
+	if (strcmp(key, "name") == 0) {
+		lua_pushstring(L, cmod_func_sym(cf));
+		return 1;
+	}
+
+	/*
+	 * Internal keys for debug only, not API.
+	 */
+	if (strncmp(key, "tt_dev.", 7) == 0) {
+		const char *subkey = &key[7];
+		if (strcmp(subkey, "refs") == 0) {
+			lua_pushnumber(L, cf->refs);
+			return 1;
+		} else if (strcmp(subkey, "key") == 0) {
+			lua_pushstring(L, cf->key);
+			return 1;
+		} else if (strcmp(subkey, "cmod.id") == 0) {
+			lua_pushnumber(L, cf->cmod->id);
+			return 1;
+		} else if (strcmp(subkey, "cmod.refs") == 0) {
+			lua_pushnumber(L, cf->cmod->refs);
+			return 1;
+		}
+	}
+	return 0;
+}
+
+/** Function representation for REPL (console). */
+static int
+lfunc_serialize(struct lua_State *L)
+{
+	struct cmod_func *cf = get_udata(L, uname_func);
+	if (cf == NULL) {
+		lua_pushnil(L);
+		return 1;
+	}
+
+	lua_createtable(L, 0, 1);
+	lua_pushstring(L, cmod_func_sym(cf));
+	lua_setfield(L, -2, "name");
+	return 1;
+}
+
+/** Collect a function. */
+static int
+lfunc_gc(struct lua_State *L)
+{
+	struct cmod_func *cf = get_udata(L, uname_func);
+	if (cf != NULL) {
+		set_udata(L, uname_func, NULL);
+		cmod_func_unref(cf);
+	}
+	return 0;
+}
+
+/** Execute a function. */
+int
+do_lfunc_call(struct cmod_func *cf, struct port *args, struct port *ret)
+{
+	struct region *region = &fiber()->gc;
+	size_t region_svp = region_used(region);
+
+	uint32_t data_sz;
+	const char *data = port_get_msgpack(args, &data_sz);
+	if (data == NULL)
+		return -1;
+
+	port_c_create(ret);
+	box_function_ctx_t ctx = {
+		.port = ret,
+	};
+
+	/*
+	 * Unlike box.schema.func cmod doesn't support
+	 * module run-time reloading and while a function
+	 * is alive a module can't disappear. Still it is
+	 * unclear if there some existing users are running
+	 * code which already tries to unload a function inside
+	 * this call execution, thus make sure the module won't
+	 * disapper inbetween.
+	 */
+	cmod_ref(cf->cmod);
+	int rc = cf->addr(&ctx, data, data + data_sz);
+	cmod_unref(cf->cmod);
+	region_truncate(region, region_svp);
+
+	if (rc != 0) {
+		if (diag_last_error(&fiber()->diag) == NULL)
+			diag_set(ClientError, ER_PROC_C, "unknown error");
+		port_destroy(ret);
+		return -1;
+	}
+
+	return rc;
+}
+
+/** Call a function by its name from the Lua code. */
+static int
+lfunc_call(struct lua_State *L)
+{
+	struct cmod_func *cf = get_udata(L, uname_func);
+	if (cf == NULL) {
+		diag_set(IllegalParams, "The function is unloaded");
+		return luaT_error(L);
+	}
+
+	lua_State *args_L = luaT_newthread(tarantool_L);
+	if (args_L == NULL)
+		return luaT_error(L);
+
+	int coro_ref = luaL_ref(tarantool_L, LUA_REGISTRYINDEX);
+	lua_xmove(L, args_L, lua_gettop(L) - 1);
+
+	struct port args;
+	port_lua_create(&args, args_L);
+	((struct port_lua *)&args)->ref = coro_ref;
+
+	struct port ret;
+
+	if (do_lfunc_call(cf, &args, &ret) != 0) {
+		port_destroy(&args);
+		return luaT_error(L);
+	}
+
+	int top = lua_gettop(L);
+	port_dump_lua(&ret, L, true);
+	int cnt = lua_gettop(L) - top;
+
+	port_destroy(&ret);
+	port_destroy(&args);
+
+	return cnt;
+}
+
+/** Initialize cmod. */
+void
+box_lua_cmod_init(struct lua_State *L)
+{
+	cmod_func_hash = mh_strnptr_new();
+	if (cmod_func_hash == NULL)
+		panic("cmod: Can't allocate func hash table");
+	cmod_hash = mh_strnptr_new();
+	if (cmod_hash == NULL)
+		panic("cmod: Can't allocate cmod hash table");
+
+	(void)L;
+	static const struct luaL_Reg top_methods[] = {
+		{ "load",		lcmod_load		},
+		{ NULL, NULL },
+	};
+	luaL_register_module(L, "cmod", top_methods);
+	lua_pop(L, 1);
+
+	static const struct luaL_Reg lcmod_methods[] = {
+		{ "unload",		lcmod_unload		},
+		{ "load",		lcmod_load_func		},
+		{ "__index",		lcmod_index		},
+		{ "__serialize",	lcmod_serialize		},
+		{ "__gc",		lcmod_gc		},
+		{ NULL, NULL },
+	};
+	luaL_register_type(L, uname_cmod, lcmod_methods);
+
+	static const struct luaL_Reg lfunc_methods[] = {
+		{ "unload",		lfunc_unload		},
+		{ "__index",		lfunc_index		},
+		{ "__serialize",	lfunc_serialize		},
+		{ "__gc",		lfunc_gc		},
+		{ "__call",		lfunc_call		},
+		{ NULL, NULL },
+	};
+	luaL_register_type(L, uname_func, lfunc_methods);
+}
diff --git a/src/box/lua/cmod.h b/src/box/lua/cmod.h
new file mode 100644
index 000000000..b369c21e0
--- /dev/null
+++ b/src/box/lua/cmod.h
@@ -0,0 +1,25 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright 2010-2021, Tarantool AUTHORS, please see AUTHORS file.
+ */
+
+#pragma once
+
+#if defined(__cplusplus)
+extern "C" {
+#endif /* defined(__cplusplus) */
+
+struct lua_State;
+
+/**
+ * Initialize cmod Lua module.
+ *
+ * @param L Lua state where to register the cmod module.
+ */
+void
+box_lua_cmod_init(struct lua_State *L);
+
+#if defined(__cplusplus)
+}
+#endif /* defined(__plusplus) */
diff --git a/src/box/lua/init.c b/src/box/lua/init.c
index fbcdfb20b..bad2b7ca9 100644
--- a/src/box/lua/init.c
+++ b/src/box/lua/init.c
@@ -60,6 +60,7 @@
 #include "box/lua/cfg.h"
 #include "box/lua/xlog.h"
 #include "box/lua/console.h"
+#include "box/lua/cmod.h"
 #include "box/lua/tuple.h"
 #include "box/lua/execute.h"
 #include "box/lua/key_def.h"
@@ -465,6 +466,7 @@ box_lua_init(struct lua_State *L)
 	box_lua_tuple_init(L);
 	box_lua_call_init(L);
 	box_lua_cfg_init(L);
+	box_lua_cmod_init(L);
 	box_lua_slab_init(L);
 	box_lua_index_init(L);
 	box_lua_space_init(L);
-- 
2.29.2

[Tarantool-patches] [PATCH v17 2/2] test: box/cfunc -- add cmod test

[Cyrill Gorcunov via Tarantool-patches]

Note that the test is disabled in suite.ini for a while
because we need to update test-run first like

 | diff --git a/pretest_clean.lua b/pretest_clean.lua
 | index 9b5ac9d..b0280c4 100644
 | --- a/pretest_clean.lua
 | +++ b/pretest_clean.lua
 | @@ -272,6 +272,7 @@ local function clean()
 |          package = true,
 |          pickle = true,
 |          popen = true,
 | +        cmod = true,
 |          pwd = true,
 |          socket = true,
 |          strict = true,

Part-of #4642

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
---
 test/box/CMakeLists.txt |   2 +
 test/box/cfunc1.c       |  58 ++++++
 test/box/cfunc2.c       | 137 +++++++++++++
 test/box/cmod.result    | 418 ++++++++++++++++++++++++++++++++++++++++
 test/box/cmod.test.lua  | 155 +++++++++++++++
 test/box/suite.ini      |   2 +-
 6 files changed, 771 insertions(+), 1 deletion(-)
 create mode 100644 test/box/cfunc1.c
 create mode 100644 test/box/cfunc2.c
 create mode 100644 test/box/cmod.result
 create mode 100644 test/box/cmod.test.lua

diff --git a/test/box/CMakeLists.txt b/test/box/CMakeLists.txt
index 06bfbbe9d..2afbeadc3 100644
--- a/test/box/CMakeLists.txt
+++ b/test/box/CMakeLists.txt
@@ -3,3 +3,5 @@ build_module(function1 function1.c)
 build_module(reload1 reload1.c)
 build_module(reload2 reload2.c)
 build_module(tuple_bench tuple_bench.c)
+build_module(cfunc1 cfunc1.c)
+build_module(cfunc2 cfunc2.c)
diff --git a/test/box/cfunc1.c b/test/box/cfunc1.c
new file mode 100644
index 000000000..f6829372a
--- /dev/null
+++ b/test/box/cfunc1.c
@@ -0,0 +1,58 @@
+#include <stdio.h>
+#include <stdbool.h>
+#include <msgpuck.h>
+
+#include "module.h"
+
+/*
+ * Before the reload functions are just declared
+ * and simply exit with zero.
+ *
+ * After the module reload we should provide real
+ * functionality.
+ */
+
+int
+cfunc_nop(box_function_ctx_t *ctx, const char *args, const char *args_end)
+{
+	(void)ctx;
+	(void)args;
+	(void)args_end;
+	return 0;
+}
+
+int
+cfunc_fetch_seq_evens(box_function_ctx_t *ctx, const char *args, const char *args_end)
+{
+	(void)ctx;
+	(void)args;
+	(void)args_end;
+	return 0;
+}
+
+int
+cfunc_multireturn(box_function_ctx_t *ctx, const char *args, const char *args_end)
+{
+	(void)ctx;
+	(void)args;
+	(void)args_end;
+	return 0;
+}
+
+int
+cfunc_args(box_function_ctx_t *ctx, const char *args, const char *args_end)
+{
+	(void)ctx;
+	(void)args;
+	(void)args_end;
+	return 0;
+}
+
+int
+cfunc_sum(box_function_ctx_t *ctx, const char *args, const char *args_end)
+{
+	(void)ctx;
+	(void)args;
+	(void)args_end;
+	return 0;
+}
diff --git a/test/box/cfunc2.c b/test/box/cfunc2.c
new file mode 100644
index 000000000..8c583e993
--- /dev/null
+++ b/test/box/cfunc2.c
@@ -0,0 +1,137 @@
+#include <stdio.h>
+#include <stdbool.h>
+#include <msgpuck.h>
+
+#include "module.h"
+
+/*
+ * Just make sure we've been called.
+ */
+int
+cfunc_nop(box_function_ctx_t *ctx, const char *args, const char *args_end)
+{
+	(void)ctx;
+	(void)args;
+	(void)args_end;
+	return 0;
+}
+
+/*
+ * Fetch first N even numbers (just to make sure the order of
+ * arguments is not screwed).
+ */
+int
+cfunc_fetch_seq_evens(box_function_ctx_t *ctx, const char *args, const char *args_end)
+{
+	int arg_count = mp_decode_array(&args);
+	if (arg_count != 1) {
+		return box_error_set(__FILE__, __LINE__, ER_PROC_C, "%s",
+				     "invalid argument count");
+	}
+	int field_count = mp_decode_array(&args);
+	if (field_count < 1) {
+		return box_error_set(__FILE__, __LINE__, ER_PROC_C, "%s",
+				     "invalid array size");
+	}
+
+	/*
+	 * We expect even numbers sequence here. The idea is
+	 * to test invalid data an issue an error from inside
+	 * of C function.
+	 */
+	for (int i = 1; i <= field_count; i++) {
+		int val = mp_decode_uint(&args);
+		int needed = 2 * i;
+		if (val != needed) {
+			char res[128];
+			snprintf(res, sizeof(res), "%s %d != %d",
+				 "invalid argument", val, needed);
+			return box_error_set(__FILE__, __LINE__,
+					     ER_PROC_C, "%s", res);
+		}
+	}
+
+	return 0;
+}
+
+/*
+ * Return one element array twice.
+ */
+int
+cfunc_multireturn(box_function_ctx_t *ctx, const char *args, const char *args_end)
+{
+	char tuple_buf[512];
+	char *d = tuple_buf;
+	d = mp_encode_array(d, 1);
+	d = mp_encode_uint(d, 1);
+	assert(d <= tuple_buf + sizeof(tuple_buf));
+
+	box_tuple_format_t *fmt = box_tuple_format_default();
+	box_tuple_t *tuple_a = box_tuple_new(fmt, tuple_buf, d);
+	if (tuple_a == NULL)
+		return -1;
+	int rc = box_return_tuple(ctx, tuple_a);
+	if (rc == 0)
+		return box_return_tuple(ctx, tuple_a);
+	return rc;
+}
+
+/*
+ * Encode int + string pair back.
+ */
+int
+cfunc_args(box_function_ctx_t *ctx, const char *args, const char *args_end)
+{
+	uint32_t arg_count = mp_decode_array(&args);
+	if (arg_count != 2) {
+		return box_error_set(__FILE__, __LINE__, ER_PROC_C, "%s",
+				     "invalid argument count");
+	}
+
+	if (mp_typeof(*args) != MP_UINT) {
+		return box_error_set(__FILE__, __LINE__, ER_PROC_C, "%s",
+				     "tuple field must be uint");
+	}
+	uint32_t num = mp_decode_uint(&args);
+
+	if (mp_typeof(*args) != MP_STR) {
+		return box_error_set(__FILE__, __LINE__, ER_PROC_C, "%s",
+				     "tuple field must be string");
+	}
+	const char *str = args;
+	uint32_t len = mp_decode_strl(&str);
+
+	char tuple_buf[512];
+	char *d = tuple_buf;
+	d = mp_encode_array(d, 2);
+	d = mp_encode_uint(d, num);
+	d = mp_encode_str(d, str, len);
+	assert(d <= tuple_buf + sizeof(tuple_buf));
+
+	box_tuple_format_t *fmt = box_tuple_format_default();
+	box_tuple_t *tuple = box_tuple_new(fmt, tuple_buf, d);
+	if (tuple == NULL)
+		return -1;
+
+	return box_return_tuple(ctx, tuple);
+}
+
+/*
+ * Sum two integers.
+ */
+int
+cfunc_sum(box_function_ctx_t *ctx, const char *args, const char *args_end)
+{
+	uint32_t arg_count = mp_decode_array(&args);
+	if (arg_count != 2) {
+		return box_error_set(__FILE__, __LINE__, ER_PROC_C, "%s",
+				     "invalid argument count");
+	}
+	uint64_t a = mp_decode_uint(&args);
+	uint64_t b = mp_decode_uint(&args);
+
+	char res[16];
+	char *end = mp_encode_uint(res, a + b);
+	box_return_mp(ctx, res, end);
+	return 0;
+}
diff --git a/test/box/cmod.result b/test/box/cmod.result
new file mode 100644
index 000000000..69099ddd9
--- /dev/null
+++ b/test/box/cmod.result
@@ -0,0 +1,418 @@
+-- test-run result file version 2
+--
+-- gh-4642: New cmod module to be able to
+-- run C stored functions on read only nodes
+-- without requirement to register them with
+-- box.schema.func help.
+--
+build_path = os.getenv("BUILDDIR")
+ | ---
+ | ...
+package.cpath = build_path..'/test/box/?.so;'..build_path..'/test/box/?.dylib;'..package.cpath
+ | ---
+ | ...
+
+cmod = require('cmod')
+ | ---
+ | ...
+fio = require('fio')
+ | ---
+ | ...
+
+ext = (jit.os == "OSX" and "dylib" or "so")
+ | ---
+ | ...
+
+cfunc_path = fio.pathjoin(build_path, "test/box/cfunc.") .. ext
+ | ---
+ | ...
+cfunc1_path = fio.pathjoin(build_path, "test/box/cfunc1.") .. ext
+ | ---
+ | ...
+cfunc2_path = fio.pathjoin(build_path, "test/box/cfunc2.") .. ext
+ | ---
+ | ...
+
+_ = pcall(fio.unlink(cfunc_path))
+ | ---
+ | ...
+fio.symlink(cfunc1_path, cfunc_path)
+ | ---
+ | - true
+ | ...
+
+_, err = pcall(cmod.load, 'non-such-module')
+ | ---
+ | ...
+assert(err ~= nil)
+ | ---
+ | - true
+ | ...
+
+-- All functions are sitting in cfunc.so.
+old_module = cmod.load('cfunc')
+ | ---
+ | ...
+assert(old_module['tt_dev.refs'] == 1)
+ | ---
+ | - true
+ | ...
+old_module_copy = cmod.load('cfunc')
+ | ---
+ | ...
+assert(old_module['tt_dev.refs'] == 2)
+ | ---
+ | - true
+ | ...
+assert(old_module_copy['tt_dev.refs'] == 2)
+ | ---
+ | - true
+ | ...
+old_module_copy:unload()
+ | ---
+ | - true
+ | ...
+assert(old_module['tt_dev.refs'] == 1)
+ | ---
+ | - true
+ | ...
+old_cfunc_nop = old_module:load('cfunc_nop')
+ | ---
+ | ...
+old_cfunc_fetch_seq_evens = old_module:load('cfunc_fetch_seq_evens')
+ | ---
+ | ...
+old_cfunc_multireturn = old_module:load('cfunc_multireturn')
+ | ---
+ | ...
+old_cfunc_args = old_module:load('cfunc_args')
+ | ---
+ | ...
+old_cfunc_sum = old_module:load('cfunc_sum')
+ | ---
+ | ...
+assert(old_module['tt_dev.refs'] == 6)
+ | ---
+ | - true
+ | ...
+
+-- Test for error on nonexisting function.
+_, err = pcall(old_module.load, old_module, 'no-such-func')
+ | ---
+ | ...
+assert(err ~= nil)
+ | ---
+ | - true
+ | ...
+
+-- Make sure they all are callable.
+old_cfunc_nop()
+ | ---
+ | ...
+old_cfunc_fetch_seq_evens()
+ | ---
+ | ...
+old_cfunc_multireturn()
+ | ---
+ | ...
+old_cfunc_args()
+ | ---
+ | ...
+old_cfunc_sum()
+ | ---
+ | ...
+
+-- Unload the module but keep old functions alive, so
+-- they keep reference to NOP module internally
+-- and still callable.
+old_module:unload()
+ | ---
+ | - true
+ | ...
+-- Test refs via function name.
+assert(old_cfunc_nop['tt_dev.cmod.refs'] == 5)
+ | ---
+ | - true
+ | ...
+old_cfunc_nop()
+ | ---
+ | ...
+old_cfunc_fetch_seq_evens()
+ | ---
+ | ...
+old_cfunc_multireturn()
+ | ---
+ | ...
+old_cfunc_args()
+ | ---
+ | ...
+old_cfunc_sum()
+ | ---
+ | ...
+
+-- The module is unloaded I should not be able
+-- to load new shared library.
+old_module:load('cfunc')
+ | ---
+ | - error: Expects function = module:load('name') but not module object passed
+ | ...
+-- Neither I should be able to unload module twise.
+old_module:unload()
+ | ---
+ | - error: The module is unloaded
+ | ...
+
+-- Clean old functions.
+old_cfunc_nop:unload()
+ | ---
+ | - true
+ | ...
+old_cfunc_fetch_seq_evens:unload()
+ | ---
+ | - true
+ | ...
+old_cfunc_multireturn:unload()
+ | ---
+ | - true
+ | ...
+old_cfunc_args:unload()
+ | ---
+ | - true
+ | ...
+assert(old_cfunc_sum['tt_dev.cmod.refs'] == 1)
+ | ---
+ | - true
+ | ...
+old_cfunc_sum:unload()
+ | ---
+ | - true
+ | ...
+
+-- And reload old module again.
+old_module = cmod.load('cfunc')
+ | ---
+ | ...
+old_module_id = old_module['tt_dev.id']
+ | ---
+ | ...
+assert(old_module['tt_dev.refs'] == 1)
+ | ---
+ | - true
+ | ...
+
+-- Overwrite module with new contents.
+_ = pcall(fio.unlink(cfunc_path))
+ | ---
+ | ...
+fio.symlink(cfunc2_path, cfunc_path)
+ | ---
+ | - true
+ | ...
+
+-- Load new module, cache should be updated.
+new_module = cmod.load('cfunc')
+ | ---
+ | ...
+new_module_id = new_module['tt_dev.id']
+ | ---
+ | ...
+
+-- Old and new module keep one reference with
+-- different IDs.
+assert(old_module['tt_dev.refs'] == 1)
+ | ---
+ | - true
+ | ...
+assert(old_module['tt_dev.refs'] == new_module['tt_dev.refs'])
+ | ---
+ | - true
+ | ...
+assert(old_module_id ~= new_module_id)
+ | ---
+ | - true
+ | ...
+
+-- All functions from old module should be loadable.
+old_cfunc_nop = old_module:load('cfunc_nop')
+ | ---
+ | ...
+old_cfunc_fetch_seq_evens = old_module:load('cfunc_fetch_seq_evens')
+ | ---
+ | ...
+old_cfunc_multireturn = old_module:load('cfunc_multireturn')
+ | ---
+ | ...
+old_cfunc_args = old_module:load('cfunc_args')
+ | ---
+ | ...
+old_cfunc_sum = old_module:load('cfunc_sum')
+ | ---
+ | ...
+assert(old_cfunc_nop['tt_dev.cmod.id'] == old_module_id)
+ | ---
+ | - true
+ | ...
+assert(old_cfunc_fetch_seq_evens['tt_dev.cmod.id'] == old_module_id)
+ | ---
+ | - true
+ | ...
+assert(old_cfunc_multireturn['tt_dev.cmod.id'] == old_module_id)
+ | ---
+ | - true
+ | ...
+assert(old_cfunc_args['tt_dev.cmod.id'] == old_module_id)
+ | ---
+ | - true
+ | ...
+assert(old_cfunc_sum['tt_dev.cmod.id'] == old_module_id)
+ | ---
+ | - true
+ | ...
+assert(old_module['tt_dev.refs'] == 6)
+ | ---
+ | - true
+ | ...
+
+-- Lookup for updated symbols.
+new_cfunc_nop = new_module:load('cfunc_nop')
+ | ---
+ | ...
+new_cfunc_fetch_seq_evens = new_module:load('cfunc_fetch_seq_evens')
+ | ---
+ | ...
+new_cfunc_multireturn = new_module:load('cfunc_multireturn')
+ | ---
+ | ...
+new_cfunc_args = new_module:load('cfunc_args')
+ | ---
+ | ...
+new_cfunc_sum = new_module:load('cfunc_sum')
+ | ---
+ | ...
+assert(new_cfunc_nop['tt_dev.cmod.id'] == new_module_id)
+ | ---
+ | - true
+ | ...
+assert(new_cfunc_fetch_seq_evens['tt_dev.cmod.id'] == new_module_id)
+ | ---
+ | - true
+ | ...
+assert(new_cfunc_multireturn['tt_dev.cmod.id'] == new_module_id)
+ | ---
+ | - true
+ | ...
+assert(new_cfunc_args['tt_dev.cmod.id'] == new_module_id)
+ | ---
+ | - true
+ | ...
+assert(new_cfunc_sum['tt_dev.cmod.id'] == new_module_id)
+ | ---
+ | - true
+ | ...
+assert(new_module['tt_dev.refs'] == 6)
+ | ---
+ | - true
+ | ...
+
+-- Call old functions.
+old_cfunc_nop()
+ | ---
+ | ...
+old_cfunc_fetch_seq_evens()
+ | ---
+ | ...
+old_cfunc_multireturn()
+ | ---
+ | ...
+old_cfunc_args()
+ | ---
+ | ...
+old_cfunc_sum()
+ | ---
+ | ...
+
+-- Call new functions.
+new_cfunc_nop()
+ | ---
+ | ...
+new_cfunc_multireturn()
+ | ---
+ | - [1]
+ | - [1]
+ | ...
+new_cfunc_fetch_seq_evens({2,4,6})
+ | ---
+ | ...
+new_cfunc_fetch_seq_evens({1,2,3})  -- error, odd numbers sequence
+ | ---
+ | - error: invalid argument 1 != 2
+ | ...
+new_cfunc_args(1, "hello")
+ | ---
+ | - [1, 'hello']
+ | ...
+new_cfunc_sum(1) -- error, one arg passed
+ | ---
+ | - error: invalid argument count
+ | ...
+new_cfunc_sum(1,2)
+ | ---
+ | - 3
+ | ...
+
+-- Cleanup old module's functions.
+old_cfunc_nop:unload()
+ | ---
+ | - true
+ | ...
+old_cfunc_fetch_seq_evens:unload()
+ | ---
+ | - true
+ | ...
+old_cfunc_multireturn:unload()
+ | ---
+ | - true
+ | ...
+old_cfunc_args:unload()
+ | ---
+ | - true
+ | ...
+old_cfunc_sum:unload()
+ | ---
+ | - true
+ | ...
+old_module:unload()
+ | ---
+ | - true
+ | ...
+
+-- Cleanup new module data.
+new_cfunc_nop:unload()
+ | ---
+ | - true
+ | ...
+new_cfunc_multireturn:unload()
+ | ---
+ | - true
+ | ...
+new_cfunc_fetch_seq_evens:unload()
+ | ---
+ | - true
+ | ...
+new_cfunc_args:unload()
+ | ---
+ | - true
+ | ...
+new_cfunc_sum:unload()
+ | ---
+ | - true
+ | ...
+new_module:unload()
+ | ---
+ | - true
+ | ...
+
+-- Cleanup the generated symlink
+_ = pcall(fio.unlink(cfunc_path))
+ | ---
+ | ...
diff --git a/test/box/cmod.test.lua b/test/box/cmod.test.lua
new file mode 100644
index 000000000..ad822df13
--- /dev/null
+++ b/test/box/cmod.test.lua
@@ -0,0 +1,155 @@
+--
+-- gh-4642: New cmod module to be able to
+-- run C stored functions on read only nodes
+-- without requirement to register them with
+-- box.schema.func help.
+--
+build_path = os.getenv("BUILDDIR")
+package.cpath = build_path..'/test/box/?.so;'..build_path..'/test/box/?.dylib;'..package.cpath
+
+cmod = require('cmod')
+fio = require('fio')
+
+ext = (jit.os == "OSX" and "dylib" or "so")
+
+cfunc_path = fio.pathjoin(build_path, "test/box/cfunc.") .. ext
+cfunc1_path = fio.pathjoin(build_path, "test/box/cfunc1.") .. ext
+cfunc2_path = fio.pathjoin(build_path, "test/box/cfunc2.") .. ext
+
+_ = pcall(fio.unlink(cfunc_path))
+fio.symlink(cfunc1_path, cfunc_path)
+
+_, err = pcall(cmod.load, 'non-such-module')
+assert(err ~= nil)
+
+-- All functions are sitting in cfunc.so.
+old_module = cmod.load('cfunc')
+assert(old_module['tt_dev.refs'] == 1)
+old_module_copy = cmod.load('cfunc')
+assert(old_module['tt_dev.refs'] == 2)
+assert(old_module_copy['tt_dev.refs'] == 2)
+old_module_copy:unload()
+assert(old_module['tt_dev.refs'] == 1)
+old_cfunc_nop = old_module:load('cfunc_nop')
+old_cfunc_fetch_seq_evens = old_module:load('cfunc_fetch_seq_evens')
+old_cfunc_multireturn = old_module:load('cfunc_multireturn')
+old_cfunc_args = old_module:load('cfunc_args')
+old_cfunc_sum = old_module:load('cfunc_sum')
+assert(old_module['tt_dev.refs'] == 6)
+
+-- Test for error on nonexisting function.
+_, err = pcall(old_module.load, old_module, 'no-such-func')
+assert(err ~= nil)
+
+-- Make sure they all are callable.
+old_cfunc_nop()
+old_cfunc_fetch_seq_evens()
+old_cfunc_multireturn()
+old_cfunc_args()
+old_cfunc_sum()
+
+-- Unload the module but keep old functions alive, so
+-- they keep reference to NOP module internally
+-- and still callable.
+old_module:unload()
+-- Test refs via function name.
+assert(old_cfunc_nop['tt_dev.cmod.refs'] == 5)
+old_cfunc_nop()
+old_cfunc_fetch_seq_evens()
+old_cfunc_multireturn()
+old_cfunc_args()
+old_cfunc_sum()
+
+-- The module is unloaded I should not be able
+-- to load new shared library.
+old_module:load('cfunc')
+-- Neither I should be able to unload module twise.
+old_module:unload()
+
+-- Clean old functions.
+old_cfunc_nop:unload()
+old_cfunc_fetch_seq_evens:unload()
+old_cfunc_multireturn:unload()
+old_cfunc_args:unload()
+assert(old_cfunc_sum['tt_dev.cmod.refs'] == 1)
+old_cfunc_sum:unload()
+
+-- And reload old module again.
+old_module = cmod.load('cfunc')
+old_module_id = old_module['tt_dev.id']
+assert(old_module['tt_dev.refs'] == 1)
+
+-- Overwrite module with new contents.
+_ = pcall(fio.unlink(cfunc_path))
+fio.symlink(cfunc2_path, cfunc_path)
+
+-- Load new module, cache should be updated.
+new_module = cmod.load('cfunc')
+new_module_id = new_module['tt_dev.id']
+
+-- Old and new module keep one reference with
+-- different IDs.
+assert(old_module['tt_dev.refs'] == 1)
+assert(old_module['tt_dev.refs'] == new_module['tt_dev.refs'])
+assert(old_module_id ~= new_module_id)
+
+-- All functions from old module should be loadable.
+old_cfunc_nop = old_module:load('cfunc_nop')
+old_cfunc_fetch_seq_evens = old_module:load('cfunc_fetch_seq_evens')
+old_cfunc_multireturn = old_module:load('cfunc_multireturn')
+old_cfunc_args = old_module:load('cfunc_args')
+old_cfunc_sum = old_module:load('cfunc_sum')
+assert(old_cfunc_nop['tt_dev.cmod.id'] == old_module_id)
+assert(old_cfunc_fetch_seq_evens['tt_dev.cmod.id'] == old_module_id)
+assert(old_cfunc_multireturn['tt_dev.cmod.id'] == old_module_id)
+assert(old_cfunc_args['tt_dev.cmod.id'] == old_module_id)
+assert(old_cfunc_sum['tt_dev.cmod.id'] == old_module_id)
+assert(old_module['tt_dev.refs'] == 6)
+
+-- Lookup for updated symbols.
+new_cfunc_nop = new_module:load('cfunc_nop')
+new_cfunc_fetch_seq_evens = new_module:load('cfunc_fetch_seq_evens')
+new_cfunc_multireturn = new_module:load('cfunc_multireturn')
+new_cfunc_args = new_module:load('cfunc_args')
+new_cfunc_sum = new_module:load('cfunc_sum')
+assert(new_cfunc_nop['tt_dev.cmod.id'] == new_module_id)
+assert(new_cfunc_fetch_seq_evens['tt_dev.cmod.id'] == new_module_id)
+assert(new_cfunc_multireturn['tt_dev.cmod.id'] == new_module_id)
+assert(new_cfunc_args['tt_dev.cmod.id'] == new_module_id)
+assert(new_cfunc_sum['tt_dev.cmod.id'] == new_module_id)
+assert(new_module['tt_dev.refs'] == 6)
+
+-- Call old functions.
+old_cfunc_nop()
+old_cfunc_fetch_seq_evens()
+old_cfunc_multireturn()
+old_cfunc_args()
+old_cfunc_sum()
+
+-- Call new functions.
+new_cfunc_nop()
+new_cfunc_multireturn()
+new_cfunc_fetch_seq_evens({2,4,6})
+new_cfunc_fetch_seq_evens({1,2,3})  -- error, odd numbers sequence
+new_cfunc_args(1, "hello")
+new_cfunc_sum(1) -- error, one arg passed
+new_cfunc_sum(1,2)
+
+-- Cleanup old module's functions.
+old_cfunc_nop:unload()
+old_cfunc_fetch_seq_evens:unload()
+old_cfunc_multireturn:unload()
+old_cfunc_args:unload()
+old_cfunc_sum:unload()
+old_module:unload()
+
+-- Cleanup new module data.
+new_cfunc_nop:unload()
+new_cfunc_multireturn:unload()
+new_cfunc_fetch_seq_evens:unload()
+new_cfunc_args:unload()
+new_cfunc_sum:unload()
+new_module:unload()
+
+-- Cleanup the generated symlink
+_ = pcall(fio.unlink(cfunc_path))
diff --git a/test/box/suite.ini b/test/box/suite.ini
index e700d0b9e..fc16c5951 100644
--- a/test/box/suite.ini
+++ b/test/box/suite.ini
@@ -2,7 +2,7 @@
 core = tarantool
 description = Database tests
 script = box.lua
-disabled = rtree_errinj.test.lua tuple_bench.test.lua
+disabled = rtree_errinj.test.lua tuple_bench.test.lua cmod.test.lua
 long_run = huge_field_map_long.test.lua
 config = engine.cfg
 release_disabled = errinj.test.lua errinj_index.test.lua rtree_errinj.test.lua upsert_errinj.test.lua iproto_stress.test.lua gh-4648-func-load-unload.test.lua
-- 
2.29.2

Re: [Tarantool-patches] [PATCH v17 1/2] box/cmod: implement cmod Lua module

[Cyrill Gorcunov via Tarantool-patches]

On Wed, Feb 10, 2021 at 03:24:47PM +0300, Cyrill Gorcunov wrote:
> 
> Once successfully loaded we can execute it. Note that unlike regular
> Lua functions the context of `C` functions is different. They never
> thrown an exception but return `true|nil, res` form where first value
> set to `nil` in case of error condition and `res` carries an error
> description.
> 
> Lets call the `cfunc_sum` with wrong number of arguments

Typo left in description. I force pushed an update (we always throw
an exception.
---
    First we should load it as
    
    ``` Lua
    m = require('cmod').load('cfunc')
    cfunc_sum = m:load('cfunc_sum')
    ```
    
    Once successfully loaded we can execute it. Lets call the
    `cfunc_sum` with wrong number of arguments
    
    ``` Lua
    cfunc_sum()
     | ---
     | - error: invalid argument count
    ```
    
    We will see the `"invalid argument count"` message in output.
    The error message has been set by the `box_error_set` in `C`
    code above.
    
    On success the sum of arguments will be printed out.
    
    ``` Lua
    cfunc_sum(1, 2)
     | ---
     | - 3
    ```