- 28 Dec, 2021 1 commit
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guybe7 authored
Preventing COFIG SET maxmemory from propagating is just the tip of the iceberg. Module that performs a write operation in a notification can cause any command to be propagated, based on server.dirty We need to come up with a better solution.
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- 27 Dec, 2021 1 commit
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guybe7 authored
There's a race between testing DBSIZE and the thread starting. If the thread hadn't started by the time we checked DBISZE, no keys will have been evicted. The correct way is to check the evicted_keys stat.
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- 22 Dec, 2021 1 commit
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guybe7 authored
The mess: Some parts use alsoPropagate for late propagation, others using an immediate one (propagate()), causing edge cases, ugly/hacky code, and the tendency for bugs The basic idea is that all commands are propagated via alsoPropagate (i.e. added to a list) and the top-most call() is responsible for going over that list and actually propagating them (and wrapping them in MULTI/EXEC if there's more than one command). This is done in the new function, propagatePendingCommands. Callers to propagatePendingCommands: 1. top-most call() (we want all nested call()s to add to the also_propagate array and just the top-most one to propagate them) - via `afterCommand` 2. handleClientsBlockedOnKeys: it is out of call() context and it may propagate stuff - via `afterCommand`. 3. handleClientsBlockedOnKeys edge case: if the looked-up key is already expired, we will propagate the expire but will not unblock any client so `afterCommand` isn't called. in that case, we have to propagate the deletion explicitly. 4. cron stuff: active-expire and eviction may also propagate stuff 5. modules: the module API allows to propagate stuff from just about anywhere (timers, keyspace notifications, threads). I could have tried to catch all the out-of-call-context places but it seemed easier to handle it in one place: when we free the context. in the spirit of what was done in call(), only the top-most freeing of a module context may cause propagation. 6. modules: when using a thread-safe ctx it's not clear when/if the ctx will be freed. we do know that the module must lock the GIL before calling RM_Replicate/RM_Call so we propagate the pending commands when releasing the GIL. A "known limitation", which were actually a bug, was fixed because of this commit (see propagate.tcl): When using a mix of RM_Call with `!` and RM_Replicate, the command would propagate out-of-order: first all the commands from RM_Call, and then the ones from RM_Replicate Another thing worth mentioning is that if, in the past, a client would issue a MULTI/EXEC with just one write command the server would blindly propagate the MULTI/EXEC too, even though it's redundant. not anymore. This commit renames propagate() to propagateNow() in order to cause conflicts in pending PRs. propagatePendingCommands is the only caller of propagateNow, which is now a static, internal helper function. Optimizations: 1. alsoPropagate will not add stuff to also_propagate if there's no AOF and replicas 2. alsoPropagate reallocs also_propagagte exponentially, to save calls to memmove Bugfixes: 1. CONFIG SET can create evictions, sending notifications which can cause to dirty++ with modules. we need to prevent it from propagating to AOF/replicas 2. We need to set current_client in RM_Call. buggy scenario: - CONFIG SET maxmemory, eviction notifications, module hook calls RM_Call - assertion in lookupKey crashes, because current_client has CONFIG SET, which isn't CMD_WRITE 3. minor: in eviction, call propagateDeletion after notification, like active-expire and all commands (we always send a notification before propagating the command)
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- 19 Apr, 2021 1 commit
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guybe7 authored
Before this commit using RM_Call without "!" could cause the master to lazy-expire a key (delete it) but without replicating to replicas. This could cause the replica's memory usage to gradually grow and could also cause consistency issues if the master and replica have a clock diff. This bug was introduced in #8617 Added a test which demonstrates that scenario.
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- 15 Mar, 2021 1 commit
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guybe7 authored
1. moduleReplicateMultiIfNeeded should use server.in_eval like moduleHandlePropagationAfterCommandCallback 2. server.in_eval could have been set to 1 and not reset back to 0 (a lot of missed early-exits after in_eval is already 1) Note: The new assertions in processCommand cover (2) and I added two module tests to cover (1) Implications: If an EVAL that failed (and thus left server.in_eval=1) runs before a module command that replicates, the replication stream will contain MULTI (because moduleReplicateMultiIfNeeded used to check server.lua_caller which is NULL at this point) but not EXEC (because server.in_eval==1) This only affects modules as module.c the only user of server.in_eval. Affects versions 6.2.0, 6.2.1
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- 10 Mar, 2021 1 commit
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guybe7 authored
Bug 1: When a module ctx is freed moduleHandlePropagationAfterCommandCallback is called and handles propagation. We want to prevent it from propagating commands that were not replicated by the same context. Example: 1. module1.foo does: RM_Replicate(cmd1); RM_Call(cmd2); RM_Replicate(cmd3) 2. RM_Replicate(cmd1) propagates MULTI and adds cmd1 to also_propagagte 3. RM_Call(cmd2) create a new ctx, calls call() and destroys the ctx. 4. moduleHandlePropagationAfterCommandCallback is called, calling alsoPropagates EXEC (Note: EXEC is still not written to socket), setting server.in_trnsaction = 0 5. RM_Replicate(cmd3) is called, propagagting yet another MULTI (now we have nested MULTI calls, which is no good) and then cmd3 We must prevent RM_Call(cmd2) from resetting server.in_transaction. REDISMODULE_CTX_MULTI_EMITTED was revived for that purpose. Bug 2: Fix issues with nested RM_Call where some have '!' and some don't. Example: 1. module1.foo does RM_Call of module2.bar without replication (i.e. no '!') 2. module2.bar internally calls RM_Call of INCR with '!' 3. at the end of module1.foo we call RM_ReplicateVerbatim We want the replica/AOF to see only module1.foo and not the INCR from module2.bar Introduced a global replication_allowed flag inside RM_Call to determine whether we need to replicate or not (even if '!' was specified) Other changes: Split beforePropagateMultiOrExec to beforePropagateMulti afterPropagateExec just for better readability
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- 22 Dec, 2020 1 commit
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Oran Agra authored
Remove read-only flag from non-keyspace cmds, different approach for EXEC to propagate MULTI (#8216) In the distant history there was only the read flag for commands, and whatever command that didn't have the read flag was a write one. Then we added the write flag, but some portions of the code still used !read Also some commands that don't work on the keyspace at all, still have the read flag. Changes in this commit: 1. remove the read-only flag from TIME, ECHO, ROLE and LASTSAVE 2. EXEC command used to decides if it should propagate a MULTI by looking at the command flags (!read & !admin). When i was about to change it to look at the write flag instead, i realized that this would cause it not to propagate a MULTI for PUBLISH, EVAL, and SCRIPT, all 3 are not marked as either a read command or a write one (as they should), but all 3 are calling forceCommandPropagation. So instead of introducing a new flag to denote a command that "writes" but not into the keyspace, and still needs propagation, i decided to rely on the forceCommandPropagation, and just fix the code to propagate MULTI when needed rather than depending on the command flags at all. The implication of my change then is that now it won't decide to propagate MULTI when it sees one of these: SELECT, PING, INFO, COMMAND, TIME and other commands which are neither read nor write. 3. Changing getNodeByQuery and clusterRedirectBlockedClientIfNeeded in cluster.c to look at !write rather than read flag. This should have no implications, since these code paths are only reachable for commands which access keys, and these are always marked as either read or write. This commit improve MULTI propagation tests, for modules and a bunch of other special cases, all of which used to pass already before that commit. the only one that test change that uncovered a change of behavior is the one that DELs a non-existing key, it used to propagate an empty multi-exec block, and no longer does.
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- 31 Mar, 2020 2 commits
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Guy Benoish authored
Makse sure call() doesn't wrap replicated commands with a redundant MULTI/EXEC Other, unrelated changes: 1. Formatting compiler warning in INFO CLIENTS 2. Use CLIENT_ID_AOF instead of UINT64_MAX
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antirez authored
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- 03 Oct, 2019 1 commit
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antirez authored
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