postgres

Commit Graph

Author	SHA1	Message	Date
Robert Haas	3aff33aa68	Fix typos. Oskari Saarenmaa	10 years ago
Bruce Momjian	ee94300446	Update copyright for 2016 Backpatch certain files through 9.1	10 years ago
Robert Haas	4efe26cbd3	shm_mq: Third attempt at fixing nowait behavior in shm_mq_receive. Commit `a1480ec1d3` purported to fix the problems with commit `b2ccb5f4e6`, but it didn't completely fix them. The problem is that the checks were performed in the wrong order, leading to a race condition. If the sender attached, sent a message, and detached after the receiver called shm_mq_get_sender and before the receiver called shm_mq_counterparty_gone, we'd incorrectly return SHM_MQ_DETACHED before all messages were read. Repair by reversing the order of operations, and add a long comment explaining why this new logic is (hopefully) correct.	10 years ago
Robert Haas	a1480ec1d3	shm_mq: Repair breakage from previous commit. If the counterparty writes some data into the queue and then detaches, it's wrong to return SHM_MQ_DETACHED right away. If we do that, we fail to read whatever was written.	10 years ago
Robert Haas	b2ccb5f4e6	shm_mq: Fix failure to notice a dead counterparty when nowait is used. The shm_mq mechanism was intended to optionally notice when the process on the other end of the queue fails to attach to the queue. It does this by allowing the user to pass a BackgroundWorkerHandle; if the background worker in question is launched and dies without attaching to the queue, then we know it never will. This logic works OK in blocking mode, but when called with nowait = true we fail to notice that this has happened due to an asymmetry in the logic. Repair. Reported off-list by Rushabh Lathia. Patch by me.	10 years ago
Robert Haas	db0f6cad48	Remove set_latch_on_sigusr1 flag. This flag has proven to be a recipe for bugs, and it doesn't seem like it can really buy anything in terms of performance. So let's just always set the process latch when we receive SIGUSR1 instead of trying to do it only when needed. Per my recent proposal on pgsql-hackers.	10 years ago
Robert Haas	4a4e6893aa	Glue layer to connect the executor to the shm_mq mechanism. The shm_mq mechanism was built to send error (and notice) messages and tuples between backends. However, shm_mq itself only deals in raw bytes. Since commit `2bd9e412f9`, we have had infrastructure for one message to redirect protocol messages to a queue and for another backend to parse them and do useful things with them. This commit introduces a somewhat analogous facility for tuples by adding a new type of DestReceiver, DestTupleQueue, which writes each tuple generated by a query into a shm_mq, and a new TupleQueueFunnel facility which reads raw tuples out of the queue and reconstructs the HeapTuple format expected by the executor. The TupleQueueFunnel abstraction supports reading from multiple tuple streams at the same time, but only in round-robin fashion. Someone could imaginably want other policies, but this should be good enough to meet our short-term needs related to parallel query, and we can always extend it later. This also makes one minor addition to the shm_mq API that didn' seem worth breaking out as a separate patch. Extracted from Amit Kapila's parallel sequential scan patch. This code was originally written by me, and then it was revised by Amit, and then it was revised some more by me.	10 years ago
Robert Haas	846f8c9483	Fix attach-related race condition in shm_mq_send_bytes. Spotted by Antonin Houska.	11 years ago
Robert Haas	df0a67f754	Fix incorrect calculation in shm_mq_receive. If some, but not all, of the length word has already been read, and the next attempt to read sees exactly the number of bytes needed to complete the length word, or fewer, then we'll incorrectly read less than all of the available data. Antonin Houska	11 years ago
Bruce Momjian	807b9e0dff	pgindent run for 9.5	11 years ago
Heikki Linnakangas	fa60fb63e5	Fix more typos in comments. Patch by CharSyam, plus a few more I spotted with grep.	11 years ago
Andres Freund	59f71a0d0b	Add a default local latch for use in signal handlers. To do so, move InitializeLatchSupport() into the new common process initialization functions, and add a new global variable MyLatch. MyLatch is usable as soon InitPostmasterChild() has been called (i.e. very early during startup). Initially it points to a process local latch that exists in all processes. InitProcess/InitAuxiliaryProcess then replaces that local latch with PGPROC->procLatch. During shutdown the reverse happens. This is primarily advantageous for two reasons: For one it simplifies dealing with the shared process latch, especially in signal handlers, because instead of having to check for MyProc, MyLatch can be used unconditionally. For another, a later patch that makes FEs/BE communication use latches, now can rely on the existence of a latch, even before having gone through InitProcess. Discussion: 20140927191243.GD5423@alap3.anarazel.de	11 years ago
Bruce Momjian	4baaf863ec	Update copyright for 2015 Backpatch certain files through 9.0	11 years ago
Robert Haas	7bb0e97407	Extend shm_mq API with new functions shm_mq_sendv, shm_mq_set_handle. shm_mq_sendv sends a message to the queue assembled from multiple locations. This is expected to be used by forthcoming patches to allow frontend/backend protocol messages to be sent via shm_mq, but might be useful for other purposes as well. shm_mq_set_handle associates a BackgroundWorkerHandle with an already-existing shm_mq_handle. This solves a timing problem when creating a shm_mq to communicate with a newly-launched background worker: if you attach to the queue first, and the background worker fails to start, you might block forever trying to do I/O on the queue; but if you start the background worker first, but then die before attaching to the queue, the background worrker might block forever trying to do I/O on the queue. This lets you attach before starting the worker (so that the worker is protected) and then associate the BackgroundWorkerHandle later (so that you are also protected). Patch by me, reviewed by Stephen Frost.	11 years ago
Robert Haas	1144ea3421	Prevent shm_mq_send from reading uninitialized memory. shm_mq_send_bytes didn't invariably initialize *bytes_written before returning, which would cause shm_mq_send to read from uninitialized memory and add the value it found there to mqh->mqh_partial_bytes. This could cause the next attempt to send a message via the queue to fail an assertion (if the queue was detached) or copy data from a garbage pointer value into the queue (if non-blocking mode was in use).	12 years ago
Bruce Momjian	0a78320057	pgindent run for 9.4 This includes removing tabs after periods in C comments, which was applied to back branches, so this change should not effect backpatching.	12 years ago
Robert Haas	5ec45bb7fa	Consistently allow reading of messages from a detached shm_mq. This was intended to work always, but the previous code only allowed it if at least one message was successfully read by the receiver before the sender detached the queue. Report by Petr Jelinek. Patch by me.	12 years ago
Robert Haas	250f8a7bbe	Rewrite comment for shm_mq_receive_bytes. The comment and the code diverged at some point before the initial commit of this feature, and I failed to notice. Noted by Tom Lane.	12 years ago
Robert Haas	3bd261ca18	Improve shm_mq portability around MAXIMUM_ALIGNOF and sizeof(Size). Revise the original decision to expose a uint64-based interface and use Size everywhere possible. Avoid assuming that MAXIMUM_ALIGNOF is 8, or making any assumption about the relationship between that value and sizeof(Size). If MAXIMUM_ALIGNOF is bigger, we'll now insert padding after the length word; if it's smaller, we are now prepared to read and write the length word in chunks. Per discussion with Tom Lane.	12 years ago
Robert Haas	ec9037df26	Single-reader, single-writer, lightweight shared message queue. This code provides infrastructure for user backends to communicate relatively easily with background workers. The message queue is structured as a ring buffer and allows messages of arbitary length to be sent and received. Patch by me. Review by KaiGai Kohei and Andres Freund.	12 years ago

20 Commits (e191a6900520a28ece9393eec2fdd69f292f12c4)