[Tarantool-patches] [PATCH luajit 6/7] sysprof: introduce Lua API

[Maxim Kokryashkin via Tarantool-patches <tarantool-patches@dev.tarantool.org>]

This commit introduces Lua API for sysprof, so it is now possible to
call it from anywhere in a Lua script. All of the parameters are passed
inside a single Lua table.
The following options are supported:
- mode:     "D" (Default mode, only virtual machine state counters)
            "L" (Leaf mode, shows the last frame on the stack)
            "C" (Callchain mode, full stack dump)
- interval: time between samples
- path:     Path to file in which profiling data should be stored

Part of tarantool/tarantool#781
---
 src/lib_misc.c                                | 224 ++++++++++++++++++
 .../misclib-sysprof-lapi.test.lua             | 105 ++++++++
 2 files changed, 329 insertions(+)
 create mode 100644 test/tarantool-tests/misclib-sysprof-lapi.test.lua

diff --git a/src/lib_misc.c b/src/lib_misc.c
index a44476e0..a3423cdd 100644
--- a/src/lib_misc.c
+++ b/src/lib_misc.c
@@ -145,6 +145,218 @@ static int on_stop_cb_default(void *opt, uint8_t *buf)
   return fclose(stream);
 }
 
+/* ----- misc.sysprof module ---------------------------------------------- */
+
+/* Not loaded by default, use: local profile = require("misc.sysprof") */
+#define LJLIB_MODULE_misc_sysprof
+
+/* The default profiling interval equals to 11 ms. */
+#define SYSPROF_DEFAULT_INTERVAL (11)
+#define SYSPROF_DEFAULT_OUTPUT "sysprof.bin"
+
+int parse_sysprof_opts(lua_State *L, struct luam_sysprof_options *opt, int idx) {
+  GCtab *options = lj_lib_checktab(L, idx);
+
+  /* get profiling mode */
+  {
+    cTValue *mode_opt = lj_tab_getstr(options, lj_str_newlit(L, "mode"));
+    char mode = 0;
+    if (mode_opt) {
+      mode = *strVdata(mode_opt);
+    }
+
+    switch (mode) {
+      case 'D':
+        opt->mode = LUAM_SYSPROF_DEFAULT;
+        break;
+      case 'L':
+        opt->mode = LUAM_SYSPROF_LEAF;
+        break;
+      case 'C':
+        opt->mode = LUAM_SYSPROF_CALLGRAPH;
+        break;
+      default:
+        return SYSPROF_ERRUSE;
+    }
+  }
+
+  /* Get profiling interval. */
+  {
+    cTValue *interval = lj_tab_getstr(options, lj_str_newlit(L, "interval"));
+    opt->interval = SYSPROF_DEFAULT_INTERVAL;
+    if (interval) {
+      int32_t signed_interval = numberVint(interval);
+      if (signed_interval < 1) {
+        return SYSPROF_ERRUSE;
+      }
+      opt->interval = signed_interval;
+    }
+  }
+
+  return SYSPROF_SUCCESS;
+}
+
+int set_output_path(const char* path, struct luam_sysprof_options *opt) {
+  lua_assert(path != NULL);
+  struct profile_ctx *ctx = opt->ctx;
+  FILE *stream = fopen(path, "wb");
+  if(!stream) {
+    return SYSPROF_ERRIO;
+  }
+  ctx->stream = stream;
+  return SYSPROF_SUCCESS;
+}
+
+const char* parse_output_path(lua_State *L, struct luam_sysprof_options *opt, int idx) {
+  /* By default, sysprof writes events to a `sysprof.bin` file. */
+  const char *path = luaL_checkstring(L, idx);
+  return path ? path : SYSPROF_DEFAULT_OUTPUT;
+}
+
+int parse_options(lua_State *L, struct luam_sysprof_options *opt)
+{
+  int status = SYSPROF_SUCCESS;
+
+  switch(lua_gettop(L)) {
+    case 2:
+      if(!(lua_isstring(L, 1) && lua_istable(L, 2))) {
+        status = SYSPROF_ERRUSE;
+        break;
+      }
+      const char* path = parse_output_path(L, opt, 1); 
+      status = set_output_path(path, opt);
+      if(status != SYSPROF_SUCCESS) 
+        break;
+
+      status = parse_sysprof_opts(L, opt, 2);
+      break;
+    case 1:
+      if(!lua_istable(L, 1)) {
+        status = SYSPROF_ERRUSE;
+        break;
+      }
+      status = parse_sysprof_opts(L, opt, 1);
+      if(status != SYSPROF_SUCCESS)
+        break;
+      status = set_output_path(SYSPROF_DEFAULT_OUTPUT, opt);
+      break;
+    default:
+      status = SYSPROF_ERRUSE;
+      break;
+  } 
+  return status;
+}
+
+int sysprof_error(lua_State *L, int status)
+{
+  switch (status) {
+    case SYSPROF_ERRUSE:
+      lua_pushnil(L);
+      lua_pushstring(L, err2msg(LJ_ERR_PROF_MISUSE));
+      lua_pushinteger(L, EINVAL);
+      return 3;
+    case SYSPROF_ERRRUN:
+      lua_pushnil(L);
+      lua_pushstring(L, err2msg(LJ_ERR_PROF_ISRUNNING));
+      lua_pushinteger(L, EINVAL);
+      return 3;
+    case SYSPROF_ERRSTOP:
+      lua_pushnil(L);
+      lua_pushstring(L, err2msg(LJ_ERR_PROF_NOTRUNNING));
+      lua_pushinteger(L, EINVAL);
+      return 3;
+    case SYSPROF_ERRIO:
+      return luaL_fileresult(L, 0, NULL);
+    default:
+      lua_assert(0);
+      return 0;
+  }
+}
+
+/* local res, err, errno = sysprof.start(options) */
+LJLIB_CF(misc_sysprof_start)
+{
+  int status = SYSPROF_SUCCESS;
+
+  struct luam_sysprof_options opt = {};
+  struct profile_ctx *ctx = NULL;
+
+  ctx = lj_mem_new(L, sizeof(*ctx));
+  ctx->g = G(L);
+  opt.ctx = ctx;
+  opt.buf = ctx->buf;
+  opt.len = STREAM_BUFFER_SIZE;
+
+  status = parse_options(L, &opt);
+  if (LJ_UNLIKELY(status != PROFILE_SUCCESS)) {
+    lj_mem_free(ctx->g, ctx, sizeof(*ctx));
+    return sysprof_error(L, status);
+  }
+
+  const struct luam_sysprof_config conf = {buffer_writer_default, on_stop_cb_default, NULL};
+  status = luaM_sysprof_configure(&conf);
+  if (LJ_UNLIKELY(status != PROFILE_SUCCESS)) {
+    return sysprof_error(L, status);
+  }
+
+  status = luaM_sysprof_start(L, &opt);
+  if (LJ_UNLIKELY(status != PROFILE_SUCCESS)) {
+    /* Allocated memory will be freed in on_stop callback. */
+    return sysprof_error(L, status);
+  }
+
+  lua_pushboolean(L, 1);
+  return 1;
+}
+
+/* local res, err, errno = profile.sysprof_stop() */
+LJLIB_CF(misc_sysprof_stop)
+{
+  int status = luaM_sysprof_stop(L);
+  if (LJ_UNLIKELY(status != PROFILE_SUCCESS)) {
+    return sysprof_error(L, status);
+  }
+  lua_pushboolean(L, 1);
+  return 1;
+}
+
+/* local counters, err, errno = sysprof.report() */
+LJLIB_CF(misc_sysprof_report)
+{
+  struct luam_sysprof_counters counters = {};
+  GCtab *data_tab = NULL;
+  GCtab *count_tab = NULL;
+
+  int status = luaM_sysprof_report(&counters);
+  if (status != SYSPROF_SUCCESS) {
+    return sysprof_error(L, status);
+  }
+
+  lua_createtable(L, 0, 3);
+  data_tab = tabV(L->top - 1);
+
+  setnumfield(L, data_tab, "samples", counters.samples);
+  setnumfield(L, data_tab, "overruns", counters.overruns);
+
+  lua_createtable(L, 0, LJ_VMST__MAX + 1);
+  count_tab = tabV(L->top - 1);
+
+  setnumfield(L, count_tab, "INTERP", counters.vmst_interp);
+  setnumfield(L, count_tab, "LFUNC",  counters.vmst_lfunc);
+  setnumfield(L, count_tab, "FFUNC",  counters.vmst_ffunc);
+  setnumfield(L, count_tab, "CFUNC",  counters.vmst_cfunc);
+  setnumfield(L, count_tab, "GC",     counters.vmst_gc);
+  setnumfield(L, count_tab, "EXIT",   counters.vmst_exit);
+  setnumfield(L, count_tab, "RECORD", counters.vmst_record);
+  setnumfield(L, count_tab, "OPT",    counters.vmst_opt);
+  setnumfield(L, count_tab, "ASM",    counters.vmst_asm);
+  setnumfield(L, count_tab, "TRACE",  counters.vmst_trace);
+
+  lua_setfield(L, -2, "vmstate");
+
+  return 1;
+}
+
 /* ----- misc.memprof module ---------------------------------------------- */
 
 #define LJLIB_MODULE_misc_memprof
@@ -237,7 +449,19 @@ LJLIB_CF(misc_memprof_stop)
 
 LUALIB_API int luaopen_misc(struct lua_State *L)
 {
+  int status = SYSPROF_SUCCESS;
+  struct luam_sysprof_config config = {};
+
+  config.writer = buffer_writer_default;
+  config.on_stop = on_stop_cb_default;
+  status = luaM_sysprof_configure(&config);
+  if (LJ_UNLIKELY(status != PROFILE_SUCCESS)) {
+    return sysprof_error(L, status);
+  }
+
   LJ_LIB_REG(L, LUAM_MISCLIBNAME, misc);
   LJ_LIB_REG(L, LUAM_MISCLIBNAME ".memprof", misc_memprof);
+  LJ_LIB_REG(L, LUAM_MISCLIBNAME ".sysprof", misc_sysprof);
+
   return 1;
 }
diff --git a/test/tarantool-tests/misclib-sysprof-lapi.test.lua b/test/tarantool-tests/misclib-sysprof-lapi.test.lua
new file mode 100644
index 00000000..17d83d1b
--- /dev/null
+++ b/test/tarantool-tests/misclib-sysprof-lapi.test.lua
@@ -0,0 +1,105 @@
+local tap = require("tap")
+
+local test = tap.test("misc-sysprof-lapi")
+test:plan(14)
+
+jit.off()
+jit.flush()
+
+local bufread = require "utils.bufread"
+local symtab = require "utils.symtab"
+
+local TMP_BINFILE = arg[0]:gsub(".+/([^/]+)%.test%.lua$", "%.%1.sysprofdata.tmp.bin")
+local BAD_PATH = arg[0]:gsub(".+/([^/]+)%.test%.lua$", "%1/sysprofdata.tmp.bin")
+
+local function payload()
+  local function fib(n)
+    if n <= 1 then
+      return n
+    end
+    return fib(n - 1) + fib(n - 2)
+  end
+  return fib(32)
+end
+
+local function generate_output(file, opts)
+  file = file or "sysprof.bin"
+  local res, err = misc.sysprof.start(file, opts)
+  assert(res, err)
+
+  payload()
+
+  res,err = misc.sysprof.stop()
+  assert(res, err)
+end
+--## GENERAL ###############################################################--
+
+--wrong profiling mode
+local res, err, errno = misc.sysprof.start{ mode = "A" }
+test:ok(res == nil and err:match("profiler misuse"))
+test:ok(type(errno) == "number")
+
+--already running
+res, err = misc.sysprof.start{ mode = "D" }
+assert(res, err)
+
+res, err, errno = misc.sysprof.start{ mode = "D" }
+print(err)
+test:ok(res == nil and err:match("profiler misuse"))
+test:ok(type(errno) == "number")
+
+res, err = misc.sysprof.stop()
+assert(res, err)
+
+--not running
+res, err, errno = misc.sysprof.stop()
+test:ok(res == nil and err:match("profiler is not running"))
+test:ok(type(errno) == "number")
+
+--bad path
+res, err, errno = misc.sysprof.start(BAD_PATH, { mode = "C" })
+test:ok(res == nil and err:match("No such file or directory"))
+test:ok(type(errno) == "number")
+
+--bad interval
+res, err, errno = misc.sysprof.start{ mode = "C", interval = -1 }
+test:ok(res == nil and err:match("profiler misuse"))
+test:ok(type(errno) == "number")
+--## DEFAULT MODE ##########################################################--
+
+res, err = pcall(generate_output, nil, { mode = "D", interval = 11 })
+if res == nil then
+  error(err)
+end
+
+local report = misc.sysprof.report()
+
+test:ok(report.samples > 0)  -- TODO: more accurate test?
+test:ok(report.vmstate.LFUNC > 0)
+test:ok(report.vmstate.TRACE == 0)
+
+-- with very big interval
+res, err = pcall(generate_output, nil, { mode = "D", interval = 1000 })
+if res == nil then
+  error(err)
+end
+
+report = misc.sysprof.report()
+test:ok(report.samples == 0)
+
+--## CALL MODE #############################################################--
+
+res, err = pcall(
+  generate_output, TMP_BINFILE, { mode = "C", interval = 11 }
+)
+if res == nil then
+  error(err)
+end
+
+local reader = bufread.new(TMP_BINFILE)
+symtab.parse(reader)
+
+os.remove(TMP_BINFILE)
+
+jit.on()
+os.exit(test:check() and 0 or 1)
-- 
2.33.0