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Merge pull request #6922 from guybe7/refix_blocked_module_memleak

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Modules: Do not auto-unblock clients if not blocked on keys
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Salvatore Sanfilippo 2020-02-27 09:53:52 +01:00 committed by GitHub
commit 79de8f3c25
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1 changed files with 22 additions and 7 deletions
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src/module.c
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@ -4290,12 +4290,15 @@ void unblockClientFromModule(client *c) {
* We must call moduleUnblockClient in order to free privdata and * We must call moduleUnblockClient in order to free privdata and
* RedisModuleBlockedClient. * RedisModuleBlockedClient.
* *
* Note that clients implementing threads and working with private data, * Note that we only do that for clients that are blocked on keys, for which
* should make sure to stop the threads or protect the private data * the contract is that the module should not call RM_UnblockClient under
* in some other way in the disconnection and timeout callback, because * normal circumstances.
* here we are going to free the private data associated with the * Clients implementing threads and working with private data should be
* blocked client. */ * aware that calling RM_UnblockClient for every blocked client is their
if (!bc->unblocked) * responsibility, and if they fail to do so memory may leak. Ideally they
* should implement the disconnect and timeout callbacks and call
* RM_UnblockClient, but any other way is also acceptable. */
if (bc->blocked_on_keys && !bc->unblocked)
moduleUnblockClient(c); moduleUnblockClient(c);
bc->client = NULL; bc->client = NULL;
@ -4409,6 +4412,10 @@ int moduleTryServeClientBlockedOnKey(client *c, robj *key) {
* *
* free_privdata: called in order to free the private data that is passed * free_privdata: called in order to free the private data that is passed
* by RedisModule_UnblockClient() call. * by RedisModule_UnblockClient() call.
*
* Note: RedisModule_UnblockClient should be called for every blocked client,
* even if client was killed, timed-out or disconnected. Failing to do so
* will result in memory leaks.
*/ */
RedisModuleBlockedClient *RM_BlockClient(RedisModuleCtx *ctx, RedisModuleCmdFunc reply_callback, RedisModuleCmdFunc timeout_callback, void (*free_privdata)(RedisModuleCtx*,void*), long long timeout_ms) { RedisModuleBlockedClient *RM_BlockClient(RedisModuleCtx *ctx, RedisModuleCmdFunc reply_callback, RedisModuleCmdFunc timeout_callback, void (*free_privdata)(RedisModuleCtx*,void*), long long timeout_ms) {
return moduleBlockClient(ctx,reply_callback,timeout_callback,free_privdata,timeout_ms, NULL,0,NULL); return moduleBlockClient(ctx,reply_callback,timeout_callback,free_privdata,timeout_ms, NULL,0,NULL);
@ -4463,7 +4470,15 @@ RedisModuleBlockedClient *RM_BlockClient(RedisModuleCtx *ctx, RedisModuleCmdFunc
* freed using the free_privdata callback provided by the user. * freed using the free_privdata callback provided by the user.
* *
* However the reply callback will be able to access the argument vector of * However the reply callback will be able to access the argument vector of
* the command, so the private data is often not needed. */ * the command, so the private data is often not needed.
*
* Note: Under normal circumstances RedisModule_UnblockClient should not be
* called for clients that are blocked on keys (Either the key will
* become ready or a timeout will occur). If for some reason you do want
* to call RedisModule_UnblockClient it is possible: Client will be
* handled as if it were timed-out (You must implement the timeout
* callback in that case).
*/
RedisModuleBlockedClient *RM_BlockClientOnKeys(RedisModuleCtx *ctx, RedisModuleCmdFunc reply_callback, RedisModuleCmdFunc timeout_callback, void (*free_privdata)(RedisModuleCtx*,void*), long long timeout_ms, RedisModuleString **keys, int numkeys, void *privdata) { RedisModuleBlockedClient *RM_BlockClientOnKeys(RedisModuleCtx *ctx, RedisModuleCmdFunc reply_callback, RedisModuleCmdFunc timeout_callback, void (*free_privdata)(RedisModuleCtx*,void*), long long timeout_ms, RedisModuleString **keys, int numkeys, void *privdata) {
return moduleBlockClient(ctx,reply_callback,timeout_callback,free_privdata,timeout_ms, keys,numkeys,privdata); return moduleBlockClient(ctx,reply_callback,timeout_callback,free_privdata,timeout_ms, keys,numkeys,privdata);
} }