On Wed, Nov 8, 2017 at 12:47 AM, Michael Paquier <michael.paqu...@gmail.com>
wrote:
>
> + /* Hook just normal backends */
> + if (session_end_hook && MyBackendId != InvalidBackendId)
> + (*session_end_hook) ();
> I have been wondering about the necessity of this restriction.
> Couldn't it be useful to just let the people implementing the hook do
> any decision-making? Tracking some non-backend shutdowns may be useful
> as well for logging purposes.
>
Also makes sense... I move down this check to hook code.
> The patch is beginning to take shape (I really like the test module
> you are implementing here!), still needs a bit more work.
>
Thanks... and your review is helping a lot!!!
> +CREATE ROLE session_hook_usr1 LOGIN;
> +CREATE ROLE session_hook_usr2 LOGIN;
> Roles created during regression tests should be prefixed with regress_.
>
Fixed.
> + if (prev_session_start_hook)
> + prev_session_start_hook();
> +
> + if (session_start_hook_enabled)
> + (void) register_session_hook("START");
> Shouldn't both be reversed?
>
Fixed.
> +/* sample sessoin end hook function */
> Typo here.
>
Fixed.
> +CREATE DATABASE session_hook_db;
> [...]
> + if (!strcmp(dbname, "session_hook_db"))
> + {
> Creating a database is usually avoided in sql files as those can be
> run on existing servers using installcheck. I am getting that this
> restriction is in place so as it is possible to create an initial
> connection to the server so as the base table to log the activity is
> created. That's a fine assumption to me. Still, I think that the
> following changes should be done:
> - Let's restrict the logging to a role name instead of a database
> name, and let's parametrize it with a setting in the temporary
> configuration file. Let's not bother about multiple role support with
> a list, for the sake of tests and simplicity only defining one role
> looks fine to me. Comments in the code should be clear about the
> dependency.
Makes sense and simplify the test code. Fixed.
> - The GUCs test_session_hooks.start_enabled and
> test_session_hooks.end_enabled are actually redundant with the
> database restriction (well, role restriction per previous comment), so
> let's remove them. Please let's also avoid ALTER SYSTEM calls in tests
> as it would impact existing installations with installcheck.
>
Also simplify the test code. Fixed.
> Impossible to tell committer's feeling about this test suite, but my
> opinion is to keep it as that's a good template example about what can
> be done with those two hooks.
>
+1
Attached new version.
Regards,
--
Fabrízio de Royes Mello
Consultoria/Coaching PostgreSQL
>> Timbira: http://www.timbira.com.br
>> Blog: http://fabriziomello.github.io
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>> Github: http://github.com/fabriziomello
diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
index 2c7260e..52a9641 100644
--- a/src/backend/tcop/postgres.c
+++ b/src/backend/tcop/postgres.c
@@ -169,6 +169,9 @@ static ProcSignalReason RecoveryConflictReason;
static MemoryContext row_description_context = NULL;
static StringInfoData row_description_buf;
+/* Hook for plugins to get control at start of session */
+session_start_hook_type session_start_hook = NULL;
+
/* ----------------------------------------------------------------
* decls for routines only used in this file
* ----------------------------------------------------------------
@@ -3857,6 +3860,9 @@ PostgresMain(int argc, char *argv[],
if (!IsUnderPostmaster)
PgStartTime = GetCurrentTimestamp();
+ if (session_start_hook)
+ (*session_start_hook) ();
+
/*
* POSTGRES main processing loop begins here
*
diff --git a/src/backend/utils/init/postinit.c b/src/backend/utils/init/postinit.c
index 20f1d27..16ec376 100644
--- a/src/backend/utils/init/postinit.c
+++ b/src/backend/utils/init/postinit.c
@@ -76,6 +76,8 @@ static bool ThereIsAtLeastOneRole(void);
static void process_startup_options(Port *port, bool am_superuser);
static void process_settings(Oid databaseid, Oid roleid);
+/* Hook for plugins to get control at end of session */
+session_end_hook_type session_end_hook = NULL;
/*** InitPostgres support ***/
@@ -1154,6 +1156,10 @@ ShutdownPostgres(int code, Datum arg)
* them explicitly.
*/
LockReleaseAll(USER_LOCKMETHOD, true);
+
+ /* Hook at session end */
+ if (session_end_hook)
+ (*session_end_hook) ();
}
diff --git a/src/include/tcop/tcopprot.h b/src/include/tcop/tcopprot.h
index f8c535c..9f05bfb 100644
--- a/src/include/tcop/tcopprot.h
+++ b/src/include/tcop/tcopprot.h
@@ -35,6 +35,13 @@ extern PGDLLIMPORT const char *debug_query_string;
extern int max_stack_depth;
extern int PostAuthDelay;
+/* Hook for plugins to get control at start and end of session */
+typedef void (*session_start_hook_type) (void);
+typedef void (*session_end_hook_type) (void);
+
+extern PGDLLIMPORT session_start_hook_type session_start_hook;
+extern PGDLLIMPORT session_end_hook_type session_end_hook;
+
/* GUC-configurable parameters */
typedef enum
diff --git a/src/test/modules/Makefile b/src/test/modules/Makefile
index b7ed0af..a3c8c1e 100644
--- a/src/test/modules/Makefile
+++ b/src/test/modules/Makefile
@@ -11,6 +11,7 @@ SUBDIRS = \
snapshot_too_old \
test_ddl_deparse \
test_extensions \
+ test_session_hooks \
test_parser \
test_pg_dump \
test_rbtree \
diff --git a/src/test/modules/test_session_hooks/.gitignore b/src/test/modules/test_session_hooks/.gitignore
new file mode 100644
index 0000000..5dcb3ff
--- /dev/null
+++ b/src/test/modules/test_session_hooks/.gitignore
@@ -0,0 +1,4 @@
+# Generated subdirectories
+/log/
+/results/
+/tmp_check/
diff --git a/src/test/modules/test_session_hooks/Makefile b/src/test/modules/test_session_hooks/Makefile
new file mode 100644
index 0000000..c5c3860
--- /dev/null
+++ b/src/test/modules/test_session_hooks/Makefile
@@ -0,0 +1,21 @@
+# src/test/modules/test_session_hooks/Makefile
+
+MODULES = test_session_hooks
+PGFILEDESC = "test_session_hooks - Test session hooks with an extension"
+
+EXTENSION = test_session_hooks
+DATA = test_session_hooks--1.0.sql
+
+REGRESS = test_session_hooks
+REGRESS_OPTS = --temp-config=$(top_srcdir)/src/test/modules/test_session_hooks/session_hooks.conf
+
+ifdef USE_PGXS
+PG_CONFIG = pg_config
+PGXS := $(shell $(PG_CONFIG) --pgxs)
+include $(PGXS)
+else
+subdir = src/test/modules/test_session_hooks
+top_builddir = ../../../..
+include $(top_builddir)/src/Makefile.global
+include $(top_srcdir)/contrib/contrib-global.mk
+endif
diff --git a/src/test/modules/test_session_hooks/README b/src/test/modules/test_session_hooks/README
new file mode 100644
index 0000000..9cb4202
--- /dev/null
+++ b/src/test/modules/test_session_hooks/README
@@ -0,0 +1,2 @@
+test_session_hooks is an example of how to use session start and end
+hooks.
diff --git a/src/test/modules/test_session_hooks/expected/test_session_hooks.out b/src/test/modules/test_session_hooks/expected/test_session_hooks.out
new file mode 100644
index 0000000..be1b949
--- /dev/null
+++ b/src/test/modules/test_session_hooks/expected/test_session_hooks.out
@@ -0,0 +1,31 @@
+CREATE ROLE regress_sess_hook_usr1 SUPERUSER LOGIN;
+CREATE ROLE regress_sess_hook_usr2 SUPERUSER LOGIN;
+\set prevdb :DBNAME
+\set prevusr :USER
+CREATE TABLE session_hook_log(id SERIAL, dbname TEXT, username TEXT, hook_at TEXT);
+SELECT * FROM session_hook_log ORDER BY id;
+ id | dbname | username | hook_at
+----+--------+----------+---------
+(0 rows)
+
+\c :prevdb regress_sess_hook_usr1
+SELECT * FROM session_hook_log ORDER BY id;
+ id | dbname | username | hook_at
+----+--------+----------+---------
+(0 rows)
+
+\c :prevdb regress_sess_hook_usr2
+SELECT * FROM session_hook_log ORDER BY id;
+ id | dbname | username | hook_at
+----+--------------------+------------------------+---------
+ 1 | contrib_regression | regress_sess_hook_usr2 | START
+(1 row)
+
+\c :prevdb :prevusr
+SELECT * FROM session_hook_log ORDER BY id;
+ id | dbname | username | hook_at
+----+--------------------+------------------------+---------
+ 1 | contrib_regression | regress_sess_hook_usr2 | START
+ 2 | contrib_regression | regress_sess_hook_usr2 | END
+(2 rows)
+
diff --git a/src/test/modules/test_session_hooks/session_hooks.conf b/src/test/modules/test_session_hooks/session_hooks.conf
new file mode 100644
index 0000000..a66e60e
--- /dev/null
+++ b/src/test/modules/test_session_hooks/session_hooks.conf
@@ -0,0 +1 @@
+shared_preload_libraries = 'test_session_hooks'
diff --git a/src/test/modules/test_session_hooks/sql/test_session_hooks.sql b/src/test/modules/test_session_hooks/sql/test_session_hooks.sql
new file mode 100644
index 0000000..5e08647
--- /dev/null
+++ b/src/test/modules/test_session_hooks/sql/test_session_hooks.sql
@@ -0,0 +1,12 @@
+CREATE ROLE regress_sess_hook_usr1 SUPERUSER LOGIN;
+CREATE ROLE regress_sess_hook_usr2 SUPERUSER LOGIN;
+\set prevdb :DBNAME
+\set prevusr :USER
+CREATE TABLE session_hook_log(id SERIAL, dbname TEXT, username TEXT, hook_at TEXT);
+SELECT * FROM session_hook_log ORDER BY id;
+\c :prevdb regress_sess_hook_usr1
+SELECT * FROM session_hook_log ORDER BY id;
+\c :prevdb regress_sess_hook_usr2
+SELECT * FROM session_hook_log ORDER BY id;
+\c :prevdb :prevusr
+SELECT * FROM session_hook_log ORDER BY id;
diff --git a/src/test/modules/test_session_hooks/test_session_hooks--1.0.sql b/src/test/modules/test_session_hooks/test_session_hooks--1.0.sql
new file mode 100644
index 0000000..16bcee9
--- /dev/null
+++ b/src/test/modules/test_session_hooks/test_session_hooks--1.0.sql
@@ -0,0 +1,4 @@
+/* src/test/modules/test_hook_session/test_hook_session--1.0.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "CREATE EXTENSION test_hook_session" to load this file. \quit
diff --git a/src/test/modules/test_session_hooks/test_session_hooks.c b/src/test/modules/test_session_hooks/test_session_hooks.c
new file mode 100644
index 0000000..1edd171
--- /dev/null
+++ b/src/test/modules/test_session_hooks/test_session_hooks.c
@@ -0,0 +1,121 @@
+/* -------------------------------------------------------------------------
+ *
+ * test_session_hooks.c
+ * Code for testing SESSION hooks.
+ *
+ * Copyright (c) 2010-2017, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ * src/test/modules/test_session_hooks/test_session_hooks.c
+ *
+ * -------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/xact.h"
+#include "commands/dbcommands.h"
+#include "executor/spi.h"
+#include "lib/stringinfo.h"
+#include "miscadmin.h"
+#include "tcop/tcopprot.h"
+#include "utils/snapmgr.h"
+#include "utils/builtins.h"
+
+PG_MODULE_MAGIC;
+
+/* Entry point of library loading/unloading */
+void _PG_init(void);
+void _PG_fini(void);
+
+/* Original Hook */
+static session_start_hook_type prev_session_start_hook = NULL;
+static session_end_hook_type prev_session_end_hook = NULL;
+
+static void
+register_session_hook(const char *hook_at)
+{
+ const char *username;
+
+ StartTransactionCommand();
+ SPI_connect();
+ PushActiveSnapshot(GetTransactionSnapshot());
+
+ username = GetUserNameFromId(GetUserId(), false);
+
+ if (!strcmp(username, "regress_sess_hook_usr2"))
+ {
+ const char *dbname;
+ int ret;
+ StringInfoData buf;
+
+ dbname = get_database_name(MyDatabaseId);
+
+ initStringInfo(&buf);
+
+ appendStringInfo(&buf, "INSERT INTO session_hook_log (dbname, username, hook_at) ");
+ appendStringInfo(&buf, "VALUES ('%s', '%s', '%s');",
+ dbname, username, hook_at);
+
+ ret = SPI_exec(buf.data, 0);
+ if (ret != SPI_OK_INSERT)
+ elog(ERROR, "SPI_execute failed: error code %d", ret);
+ }
+
+ SPI_finish();
+ PopActiveSnapshot();
+ CommitTransactionCommand();
+}
+
+/* sample session start hook function */
+static void
+sample_session_start_hook()
+{
+ /* Hook just normal backends */
+ if (MyBackendId != InvalidBackendId)
+ {
+ (void) register_session_hook("START");
+
+ if (prev_session_start_hook)
+ prev_session_start_hook();
+ }
+}
+
+/* sample session end hook function */
+static void
+sample_session_end_hook()
+{
+ /* Hook just normal backends */
+ if (MyBackendId != InvalidBackendId)
+ {
+ if (prev_session_end_hook)
+ prev_session_end_hook();
+
+ (void) register_session_hook("END");
+ }
+}
+
+/*
+ * Module Load Callback
+ */
+void
+_PG_init(void)
+{
+ /* Save Hooks for Unload */
+ prev_session_start_hook = session_start_hook;
+ prev_session_end_hook = session_end_hook;
+
+ /* Set New Hooks */
+ session_start_hook = sample_session_start_hook;
+ session_end_hook = sample_session_end_hook;
+}
+
+/*
+ * Module Unload Callback
+ */
+void
+_PG_fini(void)
+{
+ /* Uninstall Hooks */
+ session_start_hook = prev_session_start_hook;
+ session_end_hook = prev_session_end_hook;
+}
diff --git a/src/test/modules/test_session_hooks/test_session_hooks.control b/src/test/modules/test_session_hooks/test_session_hooks.control
new file mode 100644
index 0000000..7d7ef9f
--- /dev/null
+++ b/src/test/modules/test_session_hooks/test_session_hooks.control
@@ -0,0 +1,3 @@
+comment = 'Test start/end hook session with an extension'
+default_version = '1.0'
+relocatable = true
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