Merge branch 'master' into stable

Author: ololobus

Diff for: META.json

@@ -2,7 +2,7 @@
    "name": "pg_wait_sampling",
    "abstract": "Sampling based statistics of wait events",
    "description": "pg_wait_sampling provides functions for detailed per backend and per query statistics about PostgreSQL wait events",
-   "version": "1.1.1",
+   "version": "1.1.3",
    "maintainer": [
       "Alexander Korotkov <[email protected]>",
       "Ildus Kurbangaliev <[email protected]>"
@@ -21,7 +21,7 @@
      "pg_wait_sampling": {
        "file": "pg_wait_sampling--1.1.sql",
        "docfile": "README.md",
-       "version": "1.1.1",
+       "version": "1.1.3",
        "abstract": "Sampling based statistics of wait events"
      }
    },

Diff for: Makefile

@@ -28,10 +28,11 @@ $(EXTENSION)--$(EXTVERSION).sql: setup.sql
 	cat $^ > $@
 
 # Prepare the package for PGXN submission
-package: dist dist/$(EXTENSION)-$(EXTVERSION).zip
+DISTVERSION := $(shell git tag -l | tail -n 1 | cut -d 'v' -f 2)
+package: dist dist/$(EXTENSION)-$(DISTVERSION).zip
 
 dist:
 	mkdir -p dist
 
-dist/$(EXTENSION)-$(EXTVERSION).zip:
-	git archive --format zip --prefix=$(EXTENSION)-$(EXTVERSION)/ --output $@ master
+dist/$(EXTENSION)-$(DISTVERSION).zip:
+	git archive --format zip --prefix=$(EXTENSION)-$(DISTVERSION)/ --output $@ HEAD

Diff for: README.md

@@ -153,6 +153,16 @@ your bug reports.
 If you're lacking of some functionality in `pg_wait_sampling` and feeling power
 to implement it then you're welcome to make pull requests.
 
+Releases
+--------
+
+New features are developed in feature-branches and then merged into [master](https://github.com/postgrespro/pg_wait_sampling/tree/master). To make a new release:
+
+1) Bump `PGXN` version in the `META.json`.
+2) Merge [master](https://github.com/postgrespro/pg_wait_sampling/tree/master) into [stable](https://github.com/postgrespro/pg_wait_sampling/tree/stable).
+3) Tag new release in the [stable](https://github.com/postgrespro/pg_wait_sampling/tree/stable) with `git tag -a v1.1.X`, where the last digit is used for indicating compatible shared library changes and bugfixes. Second digit is used to indicate extension schema change, i.e. when `ALTER EXTENSION pg_wait_sampling UPDATE;` is required.
+4) Merge [stable](https://github.com/postgrespro/pg_wait_sampling/tree/stable) into [debian](https://github.com/postgrespro/pg_wait_sampling/tree/debian). This separate branch is used to independently support `Debian` packaging and @anayrat with @df7cb have an access there. 
+
 Authors
 -------
 

Diff for: collector.c

@@ -225,7 +225,7 @@ send_history(History *observations, shm_mq_handle *mqh)
 	{
 		ereport(WARNING,
 				(errmsg("pg_wait_sampling collector: "
-						"receiver of message queue have been detached")));
+						"receiver of message queue has been detached")));
 		return;
 	}
 	for (i = 0; i < count; i++)
@@ -238,7 +238,7 @@ send_history(History *observations, shm_mq_handle *mqh)
 		{
 			ereport(WARNING,
 					(errmsg("pg_wait_sampling collector: "
-							"receiver of message queue have been detached")));
+							"receiver of message queue has been detached")));
 			return;
 		}
 	}
@@ -260,7 +260,7 @@ send_profile(HTAB *profile_hash, shm_mq_handle *mqh)
 	{
 		ereport(WARNING,
 				(errmsg("pg_wait_sampling collector: "
-						"receiver of message queue have been detached")));
+						"receiver of message queue has been detached")));
 		return;
 	}
 	hash_seq_init(&scan_status, profile_hash);
@@ -272,7 +272,7 @@ send_profile(HTAB *profile_hash, shm_mq_handle *mqh)
 			hash_seq_term(&scan_status);
 			ereport(WARNING,
 					(errmsg("pg_wait_sampling collector: "
-							"receiver of message queue have been detached")));
+							"receiver of message queue has been detached")));
 			return;
 		}
 	}
@@ -468,7 +468,7 @@ collector_main(Datum main_arg)
 						case SHM_MQ_DETACHED:
 							ereport(WARNING,
 									(errmsg("pg_wait_sampling collector: "
-											"receiver of message queue have been "
+											"receiver of message queue has been "
 											"detached")));
 							break;
 						default:

Diff for: pg_wait_sampling.c

@@ -8,24 +8,27 @@
  *	  contrib/pg_wait_sampling/pg_wait_sampling.c
  */
 #include "postgres.h"
-#include "fmgr.h"
-#include "funcapi.h"
+
 #include "access/htup_details.h"
 #include "access/twophase.h"
 #include "catalog/pg_type.h"
+#include "fmgr.h"
+#include "funcapi.h"
 #include "miscadmin.h"
 #include "optimizer/planner.h"
 #include "pgstat.h"
-#include "storage/spin.h"
 #include "storage/ipc.h"
 #include "storage/pg_shmem.h"
 #include "storage/procarray.h"
 #include "storage/shm_mq.h"
 #include "storage/shm_toc.h"
+#include "storage/spin.h"
 #include "utils/builtins.h"
 #include "utils/datetime.h"
-#include "utils/guc.h"
 #include "utils/guc_tables.h"
+#include "utils/guc.h"
+#include "utils/memutils.h" /* TopMemoryContext.  Actually for PG 9.6 only,
+							 * but there should be no harm for others. */
 
 #include "pg_wait_sampling.h"
 
@@ -47,6 +50,11 @@ shm_mq				   *collector_mq = NULL;
 uint64				   *proc_queryids = NULL;
 CollectorShmqHeader	   *collector_hdr = NULL;
 
+/* Receiver (backend) local shm_mq pointers and lock */
+shm_mq		   *recv_mq = NULL;
+shm_mq_handle  *recv_mqh = NULL;
+LOCKTAG			queueTag;
+
 static shmem_startup_hook_type prev_shmem_startup_hook = NULL;
 static PGPROC * search_proc(int backendPid);
 static PlannedStmt *pgws_planner_hook(Query *parse,
@@ -290,6 +298,14 @@ check_shmem(void)
 	}
 }
 
+static void
+pgws_cleanup_callback(int code, Datum arg)
+{
+	elog(DEBUG3, "pg_wait_sampling cleanup: detaching shm_mq and releasing queue lock");
+	shm_mq_detach_compat(recv_mqh, recv_mq);
+	LockRelease(&queueTag, ExclusiveLock, false);
+}
+
 /*
  * Module load callback
  */
@@ -499,16 +515,14 @@ init_lock_tag(LOCKTAG *tag, uint32 lock)
 static void *
 receive_array(SHMRequest request, Size item_size, Size *count)
 {
-	LOCKTAG			queueTag;
 	LOCKTAG			collectorTag;
-	shm_mq		   *mq;
-	shm_mq_handle  *mqh;
 	shm_mq_result	res;
 	Size			len,
 					i;
 	void		   *data;
 	Pointer			result,
 					ptr;
+	MemoryContext	oldctx;
 
 	/* Ensure nobody else trying to send request to queue */
 	init_lock_tag(&queueTag, PGWS_QUEUE_LOCK);
@@ -519,7 +533,7 @@ receive_array(SHMRequest request, Size item_size, Size *count)
 	LockAcquire(&collectorTag, ExclusiveLock, false, false);
 	LockRelease(&collectorTag, ExclusiveLock, false);
 
-	mq = shm_mq_create(collector_mq, COLLECTOR_QUEUE_SIZE);
+	recv_mq = shm_mq_create(collector_mq, COLLECTOR_QUEUE_SIZE);
 	collector_hdr->request = request;
 
 	if (!collector_hdr->latch)
@@ -528,34 +542,54 @@ receive_array(SHMRequest request, Size item_size, Size *count)
 
 	SetLatch(collector_hdr->latch);
 
-	shm_mq_set_receiver(mq, MyProc);
-	mqh = shm_mq_attach(mq, NULL, NULL);
+	shm_mq_set_receiver(recv_mq, MyProc);
+
+	/*
+	 * We switch to TopMemoryContext, so that recv_mqh is allocated there
+	 * and is guaranteed to survive until before_shmem_exit callbacks are
+	 * fired.  Anyway, shm_mq_detach() will free handler on its own.
+	 *
+	 * NB: we do not pass `seg` to shm_mq_attach(), so it won't set its own
+	 * callback, i.e. we do not interfere here with shm_mq_detach_callback().
+	 */
+	oldctx = MemoryContextSwitchTo(TopMemoryContext);
+	recv_mqh = shm_mq_attach(recv_mq, NULL, NULL);
+	MemoryContextSwitchTo(oldctx);
 
-	res = shm_mq_receive(mqh, &len, &data, false);
-	if (res != SHM_MQ_SUCCESS || len != sizeof(*count))
+	/*
+	 * Now we surely attached to the shm_mq and got collector's attention.
+	 * If anything went wrong (e.g. Ctrl+C received from the client) we have
+	 * to cleanup some things, i.e. detach from the shm_mq, so collector was
+	 * able to continue responding to other requests.
+	 *
+	 * PG_ENSURE_ERROR_CLEANUP() guaranties that cleanup callback will be
+	 * fired for both ERROR and FATAL.
+	 */
+	PG_ENSURE_ERROR_CLEANUP(pgws_cleanup_callback, 0);
 	{
-		shm_mq_detach_compat(mqh, mq);
-		elog(ERROR, "Error reading mq.");
-	}
-	memcpy(count, data, sizeof(*count));
+		res = shm_mq_receive(recv_mqh, &len, &data, false);
+		if (res != SHM_MQ_SUCCESS || len != sizeof(*count))
+			elog(ERROR, "error reading mq");
 
-	result = palloc(item_size * (*count));
-	ptr = result;
+		memcpy(count, data, sizeof(*count));
 
-	for (i = 0; i < *count; i++)
-	{
-		res = shm_mq_receive(mqh, &len, &data, false);
-		if (res != SHM_MQ_SUCCESS || len != item_size)
+		result = palloc(item_size * (*count));
+		ptr = result;
+
+		for (i = 0; i < *count; i++)
 		{
-			shm_mq_detach_compat(mqh, mq);
-			elog(ERROR, "Error reading mq.");
+			res = shm_mq_receive(recv_mqh, &len, &data, false);
+			if (res != SHM_MQ_SUCCESS || len != item_size)
+				elog(ERROR, "error reading mq");
+
+			memcpy(ptr, data, item_size);
+			ptr += item_size;
 		}
-		memcpy(ptr, data, item_size);
-		ptr += item_size;
 	}
+	PG_END_ENSURE_ERROR_CLEANUP(pgws_cleanup_callback, 0);
 
-	shm_mq_detach_compat(mqh, mq);
-
+	/* We still have to detach and release lock during normal operation. */
+	shm_mq_detach_compat(recv_mqh, recv_mq);
 	LockRelease(&queueTag, ExclusiveLock, false);
 
 	return result;