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[PATCH v3 9/9] index-helper: add Windows support

From
Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Date
Jul 28, 2014, 12:03 UTC
Message-ID
<1406548995-28549-10-git-send-email-pclouds@gmail.com>
In-Reply-To
<1406548995-28549-1-git-send-email-pclouds@gmail.com>

Windows supports shared memory, but the semantics is a bit different than POSIX shm. The most noticeable thing is there's no way to get the shared memory's size by the reader, and wrapping fstat to do that would be hell. So the shm size is added near the end, hidden away from shm users (storing it in headers would cause more problems with munmap, storing it as a separate shm is even worse).

PostMessage is used instead of UNIX signals for notification. Lightweight (at least code-wise) on the client side.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
---
 config.mak.uname |  2 ++
 index-helper.c   | 48 ++++++++++++++++++++++++++++
 read-cache.c     |  6 ++++
 shm.c            | 96 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 152 insertions(+)
diff --git a/config.mak.uname b/config.mak.uname
index 7e66d80..74e764f 100644
--- a/config.mak.uname
+++ b/config.mak.uname
@@ -377,6 +377,7 @@ ifndef DEBUG
 else
 	BASIC_CFLAGS += -Zi -MDd
 endif
+	PROGRAM_OBJS += index-helper.o
 	X = .exe
 endif
 ifeq ($(uname_S),Interix)
@@ -532,6 +533,7 @@ ifneq (,$(wildcard ../THIS_IS_MSYSGIT))
 else
 	NO_CURL = YesPlease
 endif
+	PROGRAM_OBJS += index-helper.o
 endif
 ifeq ($(uname_S),QNX)
 	COMPAT_CFLAGS += -DSA_RESTART=0
diff --git a/index-helper.c b/index-helper.c
index 4262678..7c2a0e7 100644
--- a/index-helper.c
+++ b/index-helper.c
@@ -147,6 +147,51 @@ static void loop(const char *pid_file, int idle_in_seconds)
 		; /* do nothing, all is handled by signal handlers already */
 }
 
+#elif defined(GIT_WINDOWS_NATIVE)
+
+static void loop(const char *pid_file, int idle_in_seconds)
+{
+	HWND hwnd;
+	UINT_PTR timer = 0;
+	MSG msg;
+	HINSTANCE hinst = GetModuleHandle(NULL);
+	WNDCLASS wc;
+
+	/*
+	 * Emulate UNIX signals by sending WM_USER+x to a
+	 * window. Register window class and create a new window to
+	 * catch these messages.
+	 */
+	memset(&wc, 0, sizeof(wc));
+	wc.lpfnWndProc	 = DefWindowProc;
+	wc.hInstance	 = hinst;
+	wc.lpszClassName = "git-index-helper";
+	if (!RegisterClass(&wc))
+		die_errno(_("could not register new window class"));
+
+	hwnd = CreateWindow("git-index-helper", pid_file,
+			    0, 0, 0, 1, 1, NULL, NULL, hinst, NULL);
+	if (!hwnd)
+		die_errno(_("could not register new window"));
+
+	refresh(0);
+	while (1) {
+		timer = SetTimer(hwnd, timer, idle_in_seconds * 1000, NULL);
+		if (!timer)
+			die(_("no timer!"));
+		if (!GetMessage(&msg, hwnd, 0, 0) || msg.message == WM_TIMER)
+			break;
+		switch (msg.message) {
+		case WM_USER:
+			refresh(0);
+			break;
+		default:
+			/* just reset the timer */
+			break;
+		}
+	}
+}
+
 #else
 
 static void loop(const char *pid_file, int idle_in_seconds)
@@ -192,6 +237,9 @@ int main(int argc, char **argv)
 				       git_path("index-helper.pid"),
 				       LOCK_DIE_ON_ERROR);
 	strbuf_addf(&sb,
+#ifdef GIT_WINDOWS_NATIVE
+		    "HWND"
+#endif
 		    "%" PRIuMAX, (uintmax_t) getpid());
 	write_in_full(fd, sb.buf, sb.len);
 	commit_lock_file(&lock);
diff --git a/read-cache.c b/read-cache.c
index d6eb17f..0ca3345 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -1489,6 +1489,12 @@ static void poke_daemon(const struct stat *st, int refresh_cache)
 		pid_t pid = strtoul(sb.buf, &end, 10);
 		if (end && sb.buf + st->st_size == end)
 			kill(pid, refresh_cache ? SIGHUP : SIGUSR1);
+#elif defined(GIT_WINDOWS_NATIVE)
+		if (starts_with(sb.buf, "HWND")) {
+			HWND hwnd = FindWindow("git-index-helper", sb.buf);
+			PostMessage(hwnd, refresh_cache ? WM_USER : WM_USER + 1,
+				    0, 0);
+		}
 #endif
 	}
 	close(fd);
diff --git a/shm.c b/shm.c
index 4ec1a00..04d8a35 100644
--- a/shm.c
+++ b/shm.c
@@ -52,6 +52,102 @@ void git_shm_unlink(const char *fmt, ...)
 	shm_unlink(path);
 }
 
+#elif defined(GIT_WINDOWS_NATIVE)
+
+#define SHM_PATH_LEN 82	/* a little bit longer than POSIX because of "Local\\" */
+
+static ssize_t create_shm_map(int oflag, int perm, ssize_t length,
+			      void **mmap, int prot, int flags,
+			      const char *path, unsigned long page_size)
+{
+	size_t real_length;
+	void *last_page;
+	HANDLE h;
+
+	assert(perm   == 0700);
+	assert(oflag  == (O_CREAT | O_EXCL | O_RDWR));
+	assert(prot   == (PROT_READ | PROT_WRITE));
+	assert(flags  == MAP_SHARED);
+	assert(length >= 0);
+
+	real_length = length;
+	if (real_length % page_size)
+		real_length += page_size - (real_length % page_size);
+	real_length += page_size;
+	h = CreateFileMapping(INVALID_HANDLE_VALUE, NULL, PAGE_READWRITE, 0,
+			      real_length, path);
+	if (!h)
+		return -1;
+	*mmap = MapViewOfFile(h, FILE_MAP_ALL_ACCESS, 0, 0, real_length);
+	CloseHandle(h);
+	if (!*mmap)
+		return -1;
+	last_page = (unsigned char *)*mmap + real_length - page_size;
+	*(unsigned long *)last_page = length;
+	return length;
+}
+
+static ssize_t open_shm_map(int oflag, int perm, ssize_t length, void **mmap,
+			    int prot, int flags, const char *path,
+			    unsigned long page_size)
+{
+	void *last_page;
+	HANDLE h;
+
+	assert(perm   == 0700);
+	assert(oflag  == O_RDONLY);
+	assert(prot   == PROT_READ);
+	assert(flags  == MAP_SHARED);
+	assert(length <= 0);
+
+	h = OpenFileMapping(FILE_MAP_READ, FALSE, path);
+	if (!h)
+		return -1;
+	*mmap = MapViewOfFile(h, FILE_MAP_READ, 0, 0, 0);
+	CloseHandle(h);
+	if (!*mmap)
+		return -1;
+	if (length < 0) {
+		MEMORY_BASIC_INFORMATION mbi;
+		if (!VirtualQuery(*mmap, &mbi, sizeof(mbi))) {
+			UnmapViewOfFile(*mmap);
+			return -1;
+		}
+		if (mbi.RegionSize % page_size)
+			die("expected size %lu to be %lu aligned",
+				    mbi.RegionSize, page_size);
+		last_page = (unsigned char *)*mmap + mbi.RegionSize - page_size;
+		length = *(unsigned long *)last_page;
+	}
+	return length;
+}
+
+ssize_t git_shm_map(int oflag, int perm, ssize_t length, void **mmap,
+		    int prot, int flags, const char *fmt, ...)
+{
+	SYSTEM_INFO si;
+	va_list ap;
+	char path[SHM_PATH_LEN];
+
+	GetSystemInfo(&si);
+
+	strcpy(path, "Local\\");
+	va_start(ap, fmt);
+	vsprintf(path + strlen(path), fmt, ap);
+	va_end(ap);
+
+	if (oflag & O_CREAT)
+		return create_shm_map(oflag, perm, length, mmap, prot,
+				      flags, path, si.dwPageSize);
+	else
+		return open_shm_map(oflag, perm, length, mmap, prot,
+				    flags, path, si.dwPageSize);
+}
+
+void git_shm_unlink(const char *fmt, ...)
+{
+}
+
 #else
 
 ssize_t git_shm_map(int oflag, int perm, ssize_t length, void **mmap,

-- 
2.1.0.rc0.66.gb9187ad
Previous: Nguyễn Thái Ngọc Duy
Message 13 of 13 in “Speed up cache loading time”
  1. 0/9 Speed up cache loading timeNguyễn Thái Ngọc Duy, Jul 28, 2014
  2. 1/9 trace.c: add GIT_TRACE_PACK_STATS for pack usage statisticsNguyễn Thái Ngọc Duy, Jul 28, 2014
  3. 2/9 read-cache.c: fix constness of verify_hdr()Nguyễn Thái Ngọc Duy, Jul 28, 2014
  4. 3/9 read-cache: allow to keep mmap'd memory after readingNguyễn Thái Ngọc Duy, Jul 28, 2014
  5. 4/9 index-helper: new daemon for caching index and related stuffNguyễn Thái Ngọc Duy, Jul 28, 2014
  6. Eric SunshineJul 30, 2014
  7. Duy NguyenJul 30, 2014
  8. David TurnerJul 31, 2014
  9. 5/9 trace.c: add GIT_TRACE_INDEX_STATS for index statisticsNguyễn Thái Ngọc Duy, Jul 28, 2014
  10. 6/9 index-helper: add --strictNguyễn Thái Ngọc Duy, Jul 28, 2014
  11. 7/9 daemonize(): set a flag before exiting the main processNguyễn Thái Ngọc Duy, Jul 28, 2014
  12. 8/9 index-helper: add --detachNguyễn Thái Ngọc Duy, Jul 28, 2014
  13. 9/9 index-helper: add Windows supportNguyễn Thái Ngọc Duy, Jul 28, 2014

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