Create a standard function pg_sleep() to sleep for a specified amount of time.

Replace the former ad-hoc implementation used in the regression tests.
Joachim Wieland

10 files changed, 106 insertions, 29 deletions

diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 21152055aa..40b92d27d5 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -6170,6 +6170,56 @@ SELECT TIMESTAMP 'now';  -- incorrect for use with DEFAULT
      </para>
     </tip>
   </sect2>
+
+  <sect2 id="functions-datetime-delay">
+   <title>Delaying Execution</title>
+
+   <indexterm>
+    <primary>pg_sleep</primary>
+   </indexterm>
+   <indexterm>
+    <primary>sleep</primary>
+   </indexterm>
+   <indexterm>
+    <primary>delay</primary>
+   </indexterm>
+
+   <para>
+    The following function is available to delay execution of the server
+    process:
+<synopsis>
+pg_sleep(<replaceable>seconds</replaceable>)
+</synopsis>
+
+    <function>pg_sleep</function> makes the current session's process
+    sleep until <replaceable>seconds</replaceable> seconds have
+    elapsed.  <replaceable>seconds</replaceable> is a value of type
+    <type>double precision</>, so fractional-second delays can be specified.
+    For example:
+
+<programlisting>
+SELECT pg_sleep(1.5);
+</programlisting>
+   </para>
+
+   <note>
+     <para>
+      The effective resolution of the sleep interval is platform-specific;
+      0.01 seconds is a common value.  The sleep delay will be at least as long
+      as specified. It may be longer depending on factors such as server load.
+     </para>
+   </note>
+
+   <warning>
+     <para>
+      Make sure that your session does not hold more locks than necessary
+      when calling <function>pg_sleep</function>.  Otherwise other sessions
+      might have to wait for your sleeping process, slowing down the entire
+      system.
+     </para>
+   </warning>
+  </sect2>
+
  </sect1>
 
   
diff --git a/src/backend/utils/adt/misc.c b/src/backend/utils/adt/misc.c
index 6e99faa45f..ccfaf2ca80 100644
--- a/src/backend/utils/adt/misc.c
+++ b/src/backend/utils/adt/misc.c
@@ -17,6 +17,7 @@
 #include <sys/file.h>
 #include <signal.h>
 #include <dirent.h>
+#include <math.h>
 
 #include "catalog/pg_tablespace.h"
 #include "catalog/pg_type.h"
@@ -259,3 +260,51 @@ pg_tablespace_databases(PG_FUNCTION_ARGS)
 	FreeDir(fctx->dirdesc);
 	SRF_RETURN_DONE(funcctx);
 }
+
+
+/*
+ * pg_sleep - delay for N seconds
+ */
+Datum
+pg_sleep(PG_FUNCTION_ARGS)
+{
+	float8		secs = PG_GETARG_FLOAT8(0);
+	float8		endtime;
+
+	/*
+	 * We break the requested sleep into segments of no more than 1 second,
+	 * to put an upper bound on how long it will take us to respond to a
+	 * cancel or die interrupt.  (Note that pg_usleep is interruptible by
+	 * signals on some platforms but not others.)  Also, this method avoids
+	 * exposing pg_usleep's upper bound on allowed delays.
+	 *
+	 * By computing the intended stop time initially, we avoid accumulation
+	 * of extra delay across multiple sleeps.  This also ensures we won't
+	 * delay less than the specified time if pg_usleep is interrupted
+	 * by other signals such as SIGHUP.
+	 */
+
+#ifdef HAVE_INT64_TIMESTAMP
+#define GetNowFloat()	((float8) GetCurrentTimestamp() / 1000000.0)
+#else
+#define GetNowFloat()	GetCurrentTimestamp()
+#endif
+
+	endtime = GetNowFloat() + secs;
+
+	for (;;)
+	{
+		float8		delay;
+
+		CHECK_FOR_INTERRUPTS();
+		delay = endtime - GetNowFloat();
+		if (delay >= 1.0)
+			pg_usleep(1000000L);
+		else if (delay > 0.0)
+			pg_usleep((long) ceil(delay * 1000000.0));
+		else
+			break;
+	}
+
+	PG_RETURN_VOID();
+}
diff --git a/src/include/catalog/catversion.h b/src/include/catalog/catversion.h
index 7234602c0e..629dd1a4d7 100644
--- a/src/include/catalog/catversion.h
+++ b/src/include/catalog/catversion.h
@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	200601081
+#define CATALOG_VERSION_NO	200601111
 
 #endif
diff --git a/src/include/catalog/pg_proc.h b/src/include/catalog/pg_proc.h
index f1ff6a4866..b586b1eba9 100644
--- a/src/include/catalog/pg_proc.h
+++ b/src/include/catalog/pg_proc.h
@@ -3025,6 +3025,8 @@ DATA(insert OID = 2624 ( pg_read_file		PGNSP PGUID 12 f f t f v 3 25 "25 20 20"
 DESCR("Read text from a file");
 DATA(insert OID = 2625 ( pg_ls_dir			PGNSP PGUID 12 f f t t v 1 25 "25" _null_ _null_ _null_ pg_ls_dir - _null_ ));
 DESCR("List all files in a directory");
+DATA(insert OID = 2626 ( pg_sleep			PGNSP PGUID 12 f f t f v 1 2278 "701" _null_ _null_ _null_ pg_sleep - _null_ ));
+DESCR("Sleep for the specified time in seconds");
 
 
 /* Aggregates (moved here from pg_aggregate for 7.3) */
diff --git a/src/include/utils/builtins.h b/src/include/utils/builtins.h
index f5ecf6789d..09945a0f41 100644
--- a/src/include/utils/builtins.h
+++ b/src/include/utils/builtins.h
@@ -387,6 +387,7 @@ extern Datum pg_cancel_backend(PG_FUNCTION_ARGS);
 extern Datum pg_reload_conf(PG_FUNCTION_ARGS);
 extern Datum pg_tablespace_databases(PG_FUNCTION_ARGS);
 extern Datum pg_rotate_logfile(PG_FUNCTION_ARGS);
+extern Datum pg_sleep(PG_FUNCTION_ARGS);
 
 /* not_in.c */
 extern Datum int4notin(PG_FUNCTION_ARGS);
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index bd2e1328f8..d3495ffb48 100644
--- a/src/test/regress/expected/stats.out
+++ b/src/test/regress/expected/stats.out
@@ -36,8 +36,8 @@ SELECT count(*) FROM tenk2 WHERE unique1 = 1;
 (1 row)
 
 -- let stats collector catch up
-SELECT do_sleep(2);
- do_sleep 
+SELECT pg_sleep(2.0);
+ pg_sleep 
 ----------
  
 (1 row)
diff --git a/src/test/regress/input/create_function_1.source b/src/test/regress/input/create_function_1.source
index 14b90ca1a1..faa73156dc 100644
--- a/src/test/regress/input/create_function_1.source
+++ b/src/test/regress/input/create_function_1.source
@@ -52,11 +52,6 @@ CREATE FUNCTION set_ttdummy (int4)
         AS '@abs_builddir@/regress@DLSUFFIX@'
         LANGUAGE 'C' STRICT;
 
-CREATE FUNCTION do_sleep (int4)
-        RETURNS void
-        AS '@abs_builddir@/regress@DLSUFFIX@'
-        LANGUAGE 'C' STRICT;
-
 -- Things that shouldn't work:
 
 CREATE FUNCTION test1 (int) RETURNS int LANGUAGE sql
diff --git a/src/test/regress/output/create_function_1.source b/src/test/regress/output/create_function_1.source
index 7511c3f8d6..ed275b1f48 100644
--- a/src/test/regress/output/create_function_1.source
+++ b/src/test/regress/output/create_function_1.source
@@ -47,10 +47,6 @@ CREATE FUNCTION set_ttdummy (int4)
         RETURNS int4
         AS '@abs_builddir@/regress@DLSUFFIX@'
         LANGUAGE 'C' STRICT;
-CREATE FUNCTION do_sleep (int4)
-        RETURNS void
-        AS '@abs_builddir@/regress@DLSUFFIX@'
-        LANGUAGE 'C' STRICT;
 -- Things that shouldn't work:
 CREATE FUNCTION test1 (int) RETURNS int LANGUAGE sql
     AS 'SELECT ''not an integer'';';
diff --git a/src/test/regress/regress.c b/src/test/regress/regress.c
index 7cb6f82ce9..26eaa06b69 100644
--- a/src/test/regress/regress.c
+++ b/src/test/regress/regress.c
@@ -26,7 +26,6 @@ extern char *reverse_name(char *string);
 extern int	oldstyle_length(int n, text *t);
 extern Datum int44in(PG_FUNCTION_ARGS);
 extern Datum int44out(PG_FUNCTION_ARGS);
-extern Datum do_sleep(PG_FUNCTION_ARGS);
 
 
 /*
@@ -735,18 +734,3 @@ int44out(PG_FUNCTION_ARGS)
 	*--walk = '\0';
 	PG_RETURN_CSTRING(result);
 }
-
-/*
- * do_sleep - delay for N seconds
- */
-PG_FUNCTION_INFO_V1(do_sleep);
-
-Datum
-do_sleep(PG_FUNCTION_ARGS)
-{
-	int32		secs = PG_GETARG_INT32(0);
-
-	pg_usleep(secs * 1000000L);
-
-	PG_RETURN_VOID();
-}
diff --git a/src/test/regress/sql/stats.sql b/src/test/regress/sql/stats.sql
index 3589a0cf5d..75acee647d 100644
--- a/src/test/regress/sql/stats.sql
+++ b/src/test/regress/sql/stats.sql
@@ -26,7 +26,7 @@ SELECT count(*) FROM tenk2;
 SELECT count(*) FROM tenk2 WHERE unique1 = 1;
 
 -- let stats collector catch up
-SELECT do_sleep(2);
+SELECT pg_sleep(2.0);
 
 -- check effects
 SELECT st.seq_scan >= pr.seq_scan + 1,