Don't allow to disable backend assertions via the debug_assertions GUC.

The existance of the assert_enabled variable (backing the
debug_assertions GUC) reduced the amount of knowledge some static code
checkers (like coverity and various compilers) could infer from the
existance of the assertion. That could have been solved by optionally
removing the assertion_enabled variable from the Assert() et al macros
at compile time when some special macro is defined, but the resulting
complication doesn't seem to be worth the gain from having
debug_assertions. Recompiling is fast enough.

The debug_assertions GUC is still available, but readonly, as it's
useful when diagnosing problems. The commandline/client startup option
-A, which previously also allowed to enable/disable assertions, has
been removed as it doesn't serve a purpose anymore.

While at it, reduce code duplication in bufmgr.c and localbuf.c
assertions checking for spurious buffer pins. That code had to be
reindented anyway to cope with the assert_enabled removal.

doc/src/sgml/config.sgml

@@ -6722,6 +6722,26 @@ dynamic_library_path = 'C:\tools\postgresql;H:\my_project\lib;$libdir'
       </listitem>
      </varlistentry>
 
+     <varlistentry id="guc-debug-assertions" xreflabel="debug_assertions">
+      <term><varname>debug_assertions</varname> (<type>boolean</type>)
+      <indexterm>
+       <primary><varname>debug_assertions</> configuration parameter</primary>
+      </indexterm>
+      </term>
+      <listitem>
+       <para>
+        Reports whether <productname>PostgreSQL</productname> has been built
+        with assertions enabled. That is the case if the
+        macro <symbol>USE_ASSERT_CHECKING</symbol> is defined
+        when <productname>PostgreSQL</productname> is built (accomplished
+        e.g. by the <command>configure</command> option
+        <option>--enable-cassert</option>). By
+        default <productname>PostgreSQL</productname> is built without
+        assertions.
+       </para>
+      </listitem>
+     </varlistentry>
+
      <varlistentry id="guc-integer-datetimes" xreflabel="integer_datetimes">
       <term><varname>integer_datetimes</varname> (<type>boolean</type>)
       <indexterm>
@@ -6973,28 +6993,6 @@ dynamic_library_path = 'C:\tools\postgresql;H:\my_project\lib;$libdir'
       </listitem>
      </varlistentry>
 
-     <varlistentry id="guc-debug-assertions" xreflabel="debug_assertions">
-      <term><varname>debug_assertions</varname> (<type>boolean</type>)
-      <indexterm>
-       <primary><varname>debug_assertions</> configuration parameter</primary>
-      </indexterm>
-      </term>
-      <listitem>
-       <para>
-        Turns on various assertion checks. This is a debugging aid. If
-        you are experiencing strange problems or crashes you might want
-        to turn this on, as it might expose programming mistakes. To use
-        this parameter, the macro <symbol>USE_ASSERT_CHECKING</symbol>
-        must be defined when <productname>PostgreSQL</productname> is
-        built (accomplished by the <command>configure</command> option
-        <option>--enable-cassert</option>). Note that
-        <varname>debug_assertions</varname> defaults to <literal>on</>
-        if <productname>PostgreSQL</productname> has been built with
-        assertions enabled.
-       </para>
-      </listitem>
-     </varlistentry>
-
      <varlistentry id="guc-ignore-system-indexes" xreflabel="ignore_system_indexes">
       <term><varname>ignore_system_indexes</varname> (<type>boolean</type>)
       <indexterm>
@@ -7354,10 +7352,6 @@ LOG:  CleanUpLock: deleting: lock(0xb7acd844) id(24688,24696,0,0,0,1)
       </thead>
 
       <tbody>
-       <row>
-        <entry><option>-A <replaceable>x</replaceable></option></entry>
-        <entry><literal>debug_assertions = <replaceable>x</replaceable></></entry>
-       </row>
        <row>
         <entry><option>-B <replaceable>x</replaceable></option></entry>
         <entry><literal>shared_buffers = <replaceable>x</replaceable></></entry>

doc/src/sgml/ref/postgres-ref.sgml

@@ -101,18 +101,6 @@ PostgreSQL documentation
     <title>General Purpose</title>
 
     <variablelist>
-     <varlistentry>
-      <term><option>-A 0|1</option></term>
-      <listitem>
-       <para>
-        Enables run-time assertion checks, which is a debugging aid to
-        detect programming mistakes.  This option is only available if
-        assertions were enabled when <productname>PostgreSQL</> was
-        compiled. If so, the default is on.
-       </para>
-      </listitem>
-     </varlistentry>
-
      <varlistentry>
       <term><option>-B <replaceable class="parameter">nbuffers</replaceable></option></term>
       <listitem>

src/backend/access/gin/ginpostinglist.c

@@ -250,7 +250,6 @@ ginCompressPostingList(const ItemPointer ipd, int nipd, int maxsize,
 	 * Check that the encoded segment decodes back to the original items.
 	 */
 #if defined (CHECK_ENCODING_ROUNDTRIP)
-	if (assert_enabled)
 	{
 		int			ndecoded;
 		ItemPointer tmp = ginPostingListDecode(result, &ndecoded);

src/backend/commands/event_trigger.c

@@ -635,7 +635,6 @@ EventTriggerCommonSetup(Node *parsetree,
 	 * relevant command tag.
 	 */
 #ifdef USE_ASSERT_CHECKING
-	if (assert_enabled)
 	{
 		const char *dbgtag;
 

src/backend/postmaster/postmaster.c

@@ -603,14 +603,10 @@ PostmasterMain(int argc, char *argv[])
 	 * tcop/postgres.c (the option sets should not conflict) and with the
 	 * common help() function in main/main.c.
 	 */
-	while ((opt = getopt(argc, argv, "A:B:bc:C:D:d:EeFf:h:ijk:lN:nOo:Pp:r:S:sTt:W:-:")) != -1)
+	while ((opt = getopt(argc, argv, "B:bc:C:D:d:EeFf:h:ijk:lN:nOo:Pp:r:S:sTt:W:-:")) != -1)
 	{
 		switch (opt)
 		{
-			case 'A':
-				SetConfigOption("debug_assertions", optarg, PGC_POSTMASTER, PGC_S_ARGV);
-				break;
-
 			case 'B':
 				SetConfigOption("shared_buffers", optarg, PGC_POSTMASTER, PGC_S_ARGV);
 				break;

src/backend/storage/buffer/bufmgr.c

@@ -109,6 +109,7 @@ static volatile BufferDesc *BufferAlloc(SMgrRelation smgr,
 			bool *foundPtr);
 static void FlushBuffer(volatile BufferDesc *buf, SMgrRelation reln);
 static void AtProcExit_Buffers(int code, Datum arg);
+static void CheckForBufferLeaks(void);
 static int	rnode_comparator(const void *p1, const void *p2);
 
 
@@ -1699,34 +1700,13 @@ SyncOneBuffer(int buf_id, bool skip_recently_used)
 	return result | BUF_WRITTEN;
 }
 
-
 /*
  *		AtEOXact_Buffers - clean up at end of transaction.
- *
- *		As of PostgreSQL 8.0, buffer pins should get released by the
- *		ResourceOwner mechanism.  This routine is just a debugging
- *		cross-check that no pins remain.
  */
 void
 AtEOXact_Buffers(bool isCommit)
 {
-#ifdef USE_ASSERT_CHECKING
-	if (assert_enabled)
-	{
-		int			RefCountErrors = 0;
-		Buffer		b;
-
-		for (b = 1; b <= NBuffers; b++)
-		{
-			if (PrivateRefCount[b - 1] != 0)
-			{
-				PrintBufferLeakWarning(b);
-				RefCountErrors++;
-			}
-		}
-		Assert(RefCountErrors == 0);
-	}
-#endif
+	CheckForBufferLeaks();
 
 	AtEOXact_LocalBuffers(isCommit);
 }
@@ -1756,26 +1736,36 @@ AtProcExit_Buffers(int code, Datum arg)
 	AbortBufferIO();
 	UnlockBuffers();
 
+	CheckForBufferLeaks();
+
+	/* localbuf.c needs a chance too */
+	AtProcExit_LocalBuffers();
+}
+
+/*
+ *		CheckForBufferLeaks - ensure this backend holds no buffer pins
+ *
+ *		As of PostgreSQL 8.0, buffer pins should get released by the
+ *		ResourceOwner mechanism.  This routine is just a debugging
+ *		cross-check that no pins remain.
+ */
+static void
+CheckForBufferLeaks(void)
+{
 #ifdef USE_ASSERT_CHECKING
-	if (assert_enabled)
-	{
-		int			RefCountErrors = 0;
-		Buffer		b;
+	int			RefCountErrors = 0;
+	Buffer		b;
 
-		for (b = 1; b <= NBuffers; b++)
+	for (b = 1; b <= NBuffers; b++)
+	{
+		if (PrivateRefCount[b - 1] != 0)
 		{
-			if (PrivateRefCount[b - 1] != 0)
-			{
-				PrintBufferLeakWarning(b);
-				RefCountErrors++;
-			}
+			PrintBufferLeakWarning(b);
+			RefCountErrors++;
 		}
-		Assert(RefCountErrors == 0);
 	}
+	Assert(RefCountErrors == 0);
 #endif
-
-	/* localbuf.c needs a chance too */
-	AtProcExit_LocalBuffers();
 }
 
 /*

src/backend/storage/buffer/localbuf.c

@@ -491,15 +491,15 @@ GetLocalBufferStorage(void)
 }
 
 /*
- * AtEOXact_LocalBuffers - clean up at end of transaction.
+ * CheckForLocalBufferLeaks - ensure this backend holds no local buffer pins
  *
- * This is just like AtEOXact_Buffers, but for local buffers.
+ * This is just like CheckBufferLeaks(), but for local buffers.
  */
-void
-AtEOXact_LocalBuffers(bool isCommit)
+static void
+CheckForLocalBufferLeaks(void)
 {
 #ifdef USE_ASSERT_CHECKING
-	if (assert_enabled && LocalRefCount)
+	if (LocalRefCount)
 	{
 		int			RefCountErrors = 0;
 		int			i;
@@ -519,34 +519,29 @@ AtEOXact_LocalBuffers(bool isCommit)
 #endif
 }
 
+/*
+ * AtEOXact_LocalBuffers - clean up at end of transaction.
+ *
+ * This is just like AtEOXact_Buffers, but for local buffers.
+ */
+void
+AtEOXact_LocalBuffers(bool isCommit)
+{
+	CheckForLocalBufferLeaks();
+}
+
 /*
  * AtProcExit_LocalBuffers - ensure we have dropped pins during backend exit.
  *
- * This is just like AtProcExit_Buffers, but for local buffers.  We shouldn't
- * be holding any remaining pins; if we are, and assertions aren't enabled,
- * we'll fail later in DropRelFileNodeBuffers while trying to drop the temp
- * rels.
+ * This is just like AtProcExit_Buffers, but for local buffers.
  */
 void
 AtProcExit_LocalBuffers(void)
 {
-#ifdef USE_ASSERT_CHECKING
-	if (assert_enabled && LocalRefCount)
-	{
-		int			RefCountErrors = 0;
-		int			i;
-
-		for (i = 0; i < NLocBuffer; i++)
-		{
-			if (LocalRefCount[i] != 0)
-			{
-				Buffer		b = -i - 1;
-
-				PrintBufferLeakWarning(b);
-				RefCountErrors++;
-			}
-		}
-		Assert(RefCountErrors == 0);
-	}
-#endif
+	/*
+	 * We shouldn't be holding any remaining pins; if we are, and assertions
+	 * aren't enabled, we'll fail later in DropRelFileNodeBuffers while trying
+	 * to drop the temp rels.
+	 */
+	CheckForLocalBufferLeaks();
 }

src/backend/storage/lmgr/proc.c

@@ -376,7 +376,6 @@ InitProcess(void)
 	MyProc->waitLock = NULL;
 	MyProc->waitProcLock = NULL;
 #ifdef USE_ASSERT_CHECKING
-	if (assert_enabled)
 	{
 		int			i;
 
@@ -539,7 +538,6 @@ InitAuxiliaryProcess(void)
 	MyProc->waitLock = NULL;
 	MyProc->waitProcLock = NULL;
 #ifdef USE_ASSERT_CHECKING
-	if (assert_enabled)
 	{
 		int			i;
 
@@ -782,7 +780,6 @@ ProcKill(int code, Datum arg)
 	SyncRepCleanupAtProcExit();
 
 #ifdef USE_ASSERT_CHECKING
-	if (assert_enabled)
 	{
 		int			i;
 

src/backend/tcop/postgres.c

@@ -3305,14 +3305,10 @@ process_postgres_switches(int argc, char *argv[], GucContext ctx,
 	 * postmaster/postmaster.c (the option sets should not conflict) and with
 	 * the common help() function in main/main.c.
 	 */
-	while ((flag = getopt(argc, argv, "A:B:bc:C:D:d:EeFf:h:ijk:lN:nOo:Pp:r:S:sTt:v:W:-:")) != -1)
+	while ((flag = getopt(argc, argv, "B:bc:C:D:d:EeFf:h:ijk:lN:nOo:Pp:r:S:sTt:v:W:-:")) != -1)
 	{
 		switch (flag)
 		{
-			case 'A':
-				SetConfigOption("debug_assertions", optarg, ctx, gucsource);
-				break;
-
 			case 'B':
 				SetConfigOption("shared_buffers", optarg, ctx, gucsource);
 				break;

src/backend/utils/cache/catcache.c

@@ -553,41 +553,38 @@ void
 AtEOXact_CatCache(bool isCommit)
 {
 #ifdef USE_ASSERT_CHECKING
-	if (assert_enabled)
+	slist_iter	cache_iter;
+
+	slist_foreach(cache_iter, &CacheHdr->ch_caches)
 	{
-		slist_iter	cache_iter;
+		CatCache   *ccp = slist_container(CatCache, cc_next, cache_iter.cur);
+		dlist_iter	iter;
+		int			i;
 
-		slist_foreach(cache_iter, &CacheHdr->ch_caches)
+		/* Check CatCLists */
+		dlist_foreach(iter, &ccp->cc_lists)
 		{
-			CatCache   *ccp = slist_container(CatCache, cc_next, cache_iter.cur);
-			dlist_iter	iter;
-			int			i;
+			CatCList   *cl;
 
-			/* Check CatCLists */
-			dlist_foreach(iter, &ccp->cc_lists)
-			{
-				CatCList   *cl;
+			cl = dlist_container(CatCList, cache_elem, iter.cur);
+			Assert(cl->cl_magic == CL_MAGIC);
+			Assert(cl->refcount == 0);
+			Assert(!cl->dead);
+		}
 
-				cl = dlist_container(CatCList, cache_elem, iter.cur);
-				Assert(cl->cl_magic == CL_MAGIC);
-				Assert(cl->refcount == 0);
-				Assert(!cl->dead);
-			}
+		/* Check individual tuples */
+		for (i = 0; i < ccp->cc_nbuckets; i++)
+		{
+			dlist_head *bucket = &ccp->cc_bucket[i];
 
-			/* Check individual tuples */
-			for (i = 0; i < ccp->cc_nbuckets; i++)
+			dlist_foreach(iter, bucket)
 			{
-				dlist_head *bucket = &ccp->cc_bucket[i];
-
-				dlist_foreach(iter, bucket)
-				{
-					CatCTup    *ct;
+				CatCTup    *ct;
 
-					ct = dlist_container(CatCTup, cache_elem, iter.cur);
-					Assert(ct->ct_magic == CT_MAGIC);
-					Assert(ct->refcount == 0);
-					Assert(!ct->dead);
-				}
+				ct = dlist_container(CatCTup, cache_elem, iter.cur);
+				Assert(ct->ct_magic == CT_MAGIC);
+				Assert(ct->refcount == 0);
+				Assert(!ct->dead);
 			}
 		}
 	}

src/backend/utils/cache/relfilenodemap.c

@@ -220,7 +220,6 @@ RelidByRelfilenode(Oid reltablespace, Oid relfilenode)
 			found = true;
 
 #ifdef USE_ASSERT_CHECKING
-			if (assert_enabled)
 			{
 				bool		isnull;
 				Oid			check;

src/backend/utils/misc/guc.c

@@ -174,7 +174,6 @@ static void assign_syslog_ident(const char *newval, void *extra);
 static void assign_session_replication_role(int newval, void *extra);
 static bool check_temp_buffers(int *newval, void **extra, GucSource source);
 static bool check_phony_autocommit(bool *newval, void **extra, GucSource source);
-static bool check_debug_assertions(bool *newval, void **extra, GucSource source);
 static bool check_bonjour(bool *newval, void **extra, GucSource source);
 static bool check_ssl(bool *newval, void **extra, GucSource source);
 static bool check_stage_log_stats(bool *newval, void **extra, GucSource source);
@@ -413,11 +412,6 @@ extern const struct config_enum_entry dynamic_shared_memory_options[];
 /*
  * GUC option variables that are exported from this module
  */
-#ifdef USE_ASSERT_CHECKING
-bool		assert_enabled = true;
-#else
-bool		assert_enabled = false;
-#endif
 bool		log_duration = false;
 bool		Debug_print_plan = false;
 bool		Debug_print_parse = false;
@@ -500,6 +494,7 @@ static bool data_checksums;
 static int	wal_segment_size;
 static bool integer_datetimes;
 static int	effective_io_concurrency;
+static bool	assert_enabled;
 
 /* should be static, but commands/variable.c needs to get at this */
 char	   *role_string;
@@ -931,10 +926,10 @@ static struct config_bool ConfigureNamesBool[] =
 		NULL, NULL, NULL
 	},
 	{
-		{"debug_assertions", PGC_USERSET, DEVELOPER_OPTIONS,
-			gettext_noop("Turns on various assertion checks."),
-			gettext_noop("This is a debugging aid."),
-			GUC_NOT_IN_SAMPLE
+		{"debug_assertions", PGC_INTERNAL, PRESET_OPTIONS,
+			gettext_noop("Shows whether the running server has assertion checks enabled."),
+			NULL,
+			GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE
 		},
 		&assert_enabled,
 #ifdef USE_ASSERT_CHECKING
@@ -942,7 +937,7 @@ static struct config_bool ConfigureNamesBool[] =
 #else
 		false,
 #endif
-		check_debug_assertions, NULL, NULL
+		NULL, NULL, NULL
 	},
 
 	{
@@ -9117,19 +9112,6 @@ check_phony_autocommit(bool *newval, void **extra, GucSource source)
 	return true;
 }
 
-static bool
-check_debug_assertions(bool *newval, void **extra, GucSource source)
-{
-#ifndef USE_ASSERT_CHECKING
-	if (*newval)
-	{
-		GUC_check_errmsg("assertion checking is not supported by this build");
-		return false;
-	}
-#endif
-	return true;
-}
-
 static bool
 check_bonjour(bool *newval, void **extra, GucSource source)
 {

src/include/c.h

@@ -597,7 +597,7 @@ typedef NameData *Name;
  */
 #define Trap(condition, errorType) \
 	do { \
-		if ((assert_enabled) && (condition)) \
+		if (condition) \
 			ExceptionalCondition(CppAsString(condition), (errorType), \
 								 __FILE__, __LINE__); \
 	} while (0)
@@ -610,7 +610,7 @@ typedef NameData *Name;
  *	Isn't CPP fun?
  */
 #define TrapMacro(condition, errorType) \
-	((bool) ((! assert_enabled) || ! (condition) || \
+	((bool) (! (condition) || \
 			 (ExceptionalCondition(CppAsString(condition), (errorType), \
 								   __FILE__, __LINE__), 0)))
 

src/include/postgres.h

@@ -680,13 +680,10 @@ extern Datum Float8GetDatum(float8 X);
  */
 
 /*
- * These declarations supports the assertion-related macros in c.h.
- * assert_enabled is here because that file doesn't have PGDLLIMPORT in the
- * right place, and ExceptionalCondition must be present, for the backend only,
- * even when assertions are not enabled.
+ * Backend only infrastructure for the the assertion-related macros in c.h.
+ *
+ * ExceptionalCondition must be present even when assertions are not enabled.
  */
-extern PGDLLIMPORT bool assert_enabled;
-
 extern void ExceptionalCondition(const char *conditionName,
 					 const char *errorType,
 			 const char *fileName, int lineNumber) __attribute__((noreturn));