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From: Cyrill Gorcunov via Tarantool-patches <tarantool-patches@dev.tarantool.org>
To: tml <tarantool-patches@dev.tarantool.org>
Cc: Vladislav Shpilevoy <v.shpilevoy@tarantool.org>
Subject: [Tarantool-patches] [PATCH v14 03/12] module_cache: direct update a cache value on reload
Date: Wed,  3 Feb 2021 01:11:58 +0300	[thread overview]
Message-ID: <20210202221207.383101-4-gorcunov@gmail.com> (raw)
In-Reply-To: <20210202221207.383101-1-gorcunov@gmail.com>

Currently when we reload modules we remove old instance
from the module cache and then try to insert a new one
back. Note that module cache is a string based hash table:
we lookup for a pointer to the module via package name.

Thus when reload initiated we simply remove same key
from hash and put it back with a new pointer. This is
too complex and completely useless. Instead we should
simply update the value associated this the key in the
hash table. For this sake we introduce module_cache_update
helper.

Part-of #4642

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
---
 src/box/module_cache.c | 28 +++++++++++++++++++++++++---
 1 file changed, 25 insertions(+), 3 deletions(-)

diff --git a/src/box/module_cache.c b/src/box/module_cache.c
index a66b84efb..b3bfb4963 100644
--- a/src/box/module_cache.c
+++ b/src/box/module_cache.c
@@ -102,6 +102,22 @@ module_cache_add(struct module *module)
 	return 0;
 }
 
+/**
+ * Update the module cache. Since the lookup is string
+ * key based it is safe to just update the value.
+ */
+static int
+module_cache_update(const char *name, const char *name_end,
+		    struct module *module)
+{
+	mh_int_t e = mh_strnptr_find_inp(mod_hash, name, name_end - name);
+	if (e == mh_end(mod_hash))
+		return -1;
+	mh_strnptr_node(mod_hash, e)->str = module->package;
+	mh_strnptr_node(mod_hash, e)->val = module;
+	return 0;
+}
+
 /**
  * Delete a module from the modules cache.
  */
@@ -475,9 +491,15 @@ module_reload(const char *package, const char *package_end,
 		rlist_move(&new->funcs_list, &mod_sym->item);
 	}
 
-	module_cache_del(package, package_end);
-	if (module_cache_add(new) != 0)
-		goto restore;
+	if (module_cache_update(package, package_end, new) != 0) {
+		/*
+		 * Module cache must be consistent at this moment,
+		 * we've looked up for the package recently. If
+		 * someone has updated the cache in unexpected way
+		 * the consistency is lost and we must not continue.
+		 */
+		panic("module: can't update module cache (%s)", package);
+	}
 
 	module_gc(old);
 	*module = new;
-- 
2.29.2


  parent reply	other threads:[~2021-02-02 22:13 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-02 22:11 [Tarantool-patches] [PATCH v14 00/12] box: implement cmod Lua module Cyrill Gorcunov via Tarantool-patches
2021-02-02 22:11 ` [Tarantool-patches] [PATCH v14 01/12] box/func: factor out c function entry structure Cyrill Gorcunov via Tarantool-patches
2021-02-02 22:11 ` [Tarantool-patches] [PATCH v14 02/12] module_cache: move module handling into own subsystem Cyrill Gorcunov via Tarantool-patches
2021-02-02 22:11 ` Cyrill Gorcunov via Tarantool-patches [this message]
2021-02-02 22:11 ` [Tarantool-patches] [PATCH v14 04/12] module_cache: rename calls to ref in module structure Cyrill Gorcunov via Tarantool-patches
2021-02-02 22:12 ` [Tarantool-patches] [PATCH v14 05/12] module_cache: add comment about weird resolving Cyrill Gorcunov via Tarantool-patches
2021-02-02 22:12 ` [Tarantool-patches] [PATCH v14 06/12] module_cache: module_reload - drop redundant parameter Cyrill Gorcunov via Tarantool-patches
2021-02-02 22:12 ` [Tarantool-patches] [PATCH v14 07/12] module_cache: use references as a main usage counter Cyrill Gorcunov via Tarantool-patches
2021-02-02 22:12 ` [Tarantool-patches] [PATCH v14 08/12] module_cache: make module to carry hash it belongs to Cyrill Gorcunov via Tarantool-patches
2021-02-02 22:12 ` [Tarantool-patches] [PATCH v14 09/12] module_cache: use own hash for box.schema.func requests Cyrill Gorcunov via Tarantool-patches
2021-02-02 22:12 ` [Tarantool-patches] [PATCH v14 10/12] module_cache: provide module_load/unload calls Cyrill Gorcunov via Tarantool-patches
2021-02-02 22:12 ` [Tarantool-patches] [PATCH v14 11/12] box/cmod: implement cmod Lua module Cyrill Gorcunov via Tarantool-patches
2021-02-02 22:12 ` [Tarantool-patches] [PATCH v14 12/12] test: box/cfunc -- add cmod test Cyrill Gorcunov via Tarantool-patches

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