On 09/17/2014 08:27 PM, Craig Ringer wrote:
> Hi all
>
> Attached is a patch to switch 9.5 over to using the
> GetSystemTimeAsFileTime call instead of separate GetSystemTime and
> SystemTimeToFileTime calls.
Following on from my prior patch that switches to using
GetSystemTimeAsFileTime, I now attach a two-patch series that also adds
support for GetFileTimePreciseAsFileTime where it is available.
Details in the patch commit messages.
These should apply fine with "git am", or at worst "git am --3way".
Otherwise you can just grab them from the working tree:
https://github.com/ringerc/postgres/tree/win32_use_filetime
--
Craig Ringer http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
>From 7f4891ee288a6b36828ccf23f63396d35925311e Mon Sep 17 00:00:00 2001
From: Craig Ringer <cr...@2ndquadrant.com>
Date: Thu, 18 Sep 2014 23:02:14 +0800
Subject: [PATCH 2/2] Use GetSystemTimePreciseAsFileTime when available
This will cause PostgreSQL on Windows 8 or Windows Server 2012 to
obtain high-resolution timestamps while allowing the same binaries
to run without problems on older releases.
---
src/backend/main/main.c | 6 ++++++
src/include/port.h | 2 ++
src/port/gettimeofday.c | 54 +++++++++++++++++++++++++++++++++++++++++++++++--
3 files changed, 60 insertions(+), 2 deletions(-)
diff --git a/src/backend/main/main.c b/src/backend/main/main.c
index c1116e0..6ddf147 100644
--- a/src/backend/main/main.c
+++ b/src/backend/main/main.c
@@ -259,6 +259,12 @@ startup_hacks(const char *progname)
/* In case of general protection fault, don't show GUI popup box */
SetErrorMode(SEM_FAILCRITICALERRORS | SEM_NOGPFAULTERRORBOX);
+
+#ifndef HAVE_GETTIMEOFDAY
+ /* Figure out which syscall to use to capture timestamp information */
+ init_win32_gettimeofday();
+#endif
+
}
#endif /* WIN32 */
diff --git a/src/include/port.h b/src/include/port.h
index 9f8465e..4f8af0a 100644
--- a/src/include/port.h
+++ b/src/include/port.h
@@ -328,6 +328,8 @@ extern FILE *pgwin32_popen(const char *command, const char *type);
#ifndef HAVE_GETTIMEOFDAY
/* Last parameter not used */
extern int gettimeofday(struct timeval * tp, struct timezone * tzp);
+/* On windows we need to call some backend start setup for accurate timing */
+extern void init_win32_gettimeofday(void);
#endif
#else /* !WIN32 */
diff --git a/src/port/gettimeofday.c b/src/port/gettimeofday.c
index 73ec406..63c3a79 100644
--- a/src/port/gettimeofday.c
+++ b/src/port/gettimeofday.c
@@ -30,14 +30,64 @@
#include <sys/time.h>
+#ifndef FRONTEND
+#include <utils/elog.h>
+#endif
+
/* FILETIME of Jan 1 1970 00:00:00. */
static const unsigned __int64 epoch = UINT64CONST(116444736000000000);
/*
+ * Both GetSystemTimeAsFileTime and GetSystemTimePreciseAsFileTime share a
+ * signature, so we can just store a pointer to whichever we find. This
+ * is the pointer's type.
+ */
+typedef VOID (WINAPI *PgGetSystemTimeFn)(LPFILETIME);
+/* Storage for the function we pick at runtime */
+static PgGetSystemTimeFn pg_get_system_time = NULL;
+
+/*
+ * During backend startup, determine if GetSystemTimePreciseAsFileTime is
+ * available and use it; if not, fall back to GetSystemTimeAsFileTime.
+ */
+void
+init_win32_gettimeofday(void)
+{
+ /*
+ * Because it's guaranteed that kernel32.dll will be linked into our
+ * address space already, we don't need to LoadLibrary it and worry about
+ * closing it afterwards, so we're not using Pg's dlopen/dlsym() wrapper.
+ *
+ * We'll just look up the address of GetSystemTimePreciseAsFileTime if
+ * present.
+ *
+ * While we could look up the Windows version and skip this on Windows
+ * versions below Windows 8 / Windows Server 2012 there isn't much point,
+ * and determining the windows version is its self somewhat Windows version
+ * and development SDK specific...
+ */
+ pg_get_system_time = (PgGetSystemTimeFn) GetProcAddress(
+ GetModuleHandle(TEXT("kernel32.dll")),
+ "GetSystemRimePreciseAsFileTime");
+ if (pg_get_system_time == NULL)
+ {
+ DWORD errcode = GetLastError();
+#ifndef FRONTEND
+ if (errcode != ERROR_PROC_NOT_FOUND)
+ {
+ elog(DEBUG1, "GetProcAddress(\"GetSystemRimePreciseAsFileTime\") on kernel32.dll failed with error code %d not expected ERROR_PROC_NOT_FOUND(127)", errcode);
+ }
+#endif
+ pg_get_system_time = &GetSystemTimeAsFileTime;
+ }
+
+}
+
+/*
* timezone information is stored outside the kernel so tzp isn't used anymore.
*
- * Note: this function is not for Win32 high precision timing purpose. See
+ * Note: this function is not for Win32 high precision timing purposes. See
* elapsed_time().
*/
int
@@ -46,7 +96,7 @@ gettimeofday(struct timeval * tp, struct timezone * tzp)
FILETIME file_time;
ULARGE_INTEGER ularge;
- GetSystemTimeAsFileTime(&file_time);
+ (*pg_get_system_time)(&file_time);
ularge.LowPart = file_time.dwLowDateTime;
ularge.HighPart = file_time.dwHighDateTime;
--
1.9.3
>From 337f1e4894bf7071c6d0c24a77c433a0b9e0cc81 Mon Sep 17 00:00:00 2001
From: Craig Ringer <cr...@2ndquadrant.com>
Date: Fri, 12 Sep 2014 12:41:35 +0800
Subject: [PATCH 1/2] Use GetSystemTimeAsFileTime directly in windows
gettimeofday
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
PostgreSQL was calling GetSystemTime followed by SystemTimeToFileTime in the
win32 port gettimeofday function. This is not necessary and limits the reported
precision to the 1ms granularity that the SYSTEMTIME struct can represent. By
using GetSystemTimeAsFileTime we avoid unnecessary conversions and capture
timestamps at 100ns granularity, which is then rounded to 1µs granularity for
storage in a PostgreSQL timestamp.
On most Windows systems this change will actually have no significant effect as
the system timer tick is typically between 1ms and 15ms depending on what timer
resolution currently running applications have requested. You can check this
with clockres.exe from sysinternals. Despite the platform limiation this change
still permits capture of finer timestamps where the system is capable of
producing them and it gets rid of an unnecessary syscall.
Future work may permit use of GetSystemTimePreciseAsFileTime on Windows 8 and
Windows Server 2012 for higher resolution time capture. This call has the same
interface as GetSystemTimeAsFileTime.
---
src/port/gettimeofday.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)
diff --git a/src/port/gettimeofday.c b/src/port/gettimeofday.c
index 75a9199..73ec406 100644
--- a/src/port/gettimeofday.c
+++ b/src/port/gettimeofday.c
@@ -44,16 +44,14 @@ int
gettimeofday(struct timeval * tp, struct timezone * tzp)
{
FILETIME file_time;
- SYSTEMTIME system_time;
ULARGE_INTEGER ularge;
- GetSystemTime(&system_time);
- SystemTimeToFileTime(&system_time, &file_time);
+ GetSystemTimeAsFileTime(&file_time);
ularge.LowPart = file_time.dwLowDateTime;
ularge.HighPart = file_time.dwHighDateTime;
tp->tv_sec = (long) ((ularge.QuadPart - epoch) / 10000000L);
- tp->tv_usec = (long) (system_time.wMilliseconds * 1000);
+ tp->tv_usec = (long) (((ularge.QuadPart - epoch) % 10000000L) / 10);
return 0;
}
--
1.9.3
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