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[PATCH v2 07/17] read-cache: add watchman 'WAMA' extension

From
David Turner <dturner@twopensource.com>
Date
Mar 19, 2016, 01:04 UTC
Message-ID
<1458349490-1704-8-git-send-email-dturner@twopensource.com>
In-Reply-To
<1458349490-1704-1-git-send-email-dturner@twopensource.com>
From: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>

The extension contains a bitmap, one bit for each entry in the index. If the n-th bit is zero, the n-th entry is considered unchanged, we can ce_mark_uptodate() it without refreshing. If the bit is non-zero and we found out the corresponding file is clean after refresh, we can clear the bit.

In addition, there's a list of directories in the untracked-cache to invalidate (because they have new or modified entries).

The 'skipping refresh' bit is not in this patch yet as we would need watchman. More details in later patches.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
---
 cache.h      |   4 ++
 dir.h        |   3 ++
 read-cache.c | 117 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 3 files changed, 122 insertions(+), 2 deletions(-)
diff --git a/cache.h b/cache.h
index d386722..5b10d52 100644
--- a/cache.h
+++ b/cache.h
@@ -182,6 +182,8 @@ struct cache_entry {
 #define CE_VALID     (0x8000)
 #define CE_STAGESHIFT 12
 
+#define CE_WATCHMAN_DIRTY  (0x0001)
+
 /*
  * Range 0xFFFF0FFF in ce_flags is divided into
  * two parts: in-memory flags and on-disk ones.
@@ -320,6 +322,7 @@ static inline unsigned int canon_mode(unsigned int mode)
 #define CACHE_TREE_CHANGED	(1 << 5)
 #define SPLIT_INDEX_ORDERED	(1 << 6)
 #define UNTRACKED_CHANGED	(1 << 7)
+#define WATCHMAN_CHANGED	(1 << 8)
 
 struct split_index;
 struct untracked_cache;
@@ -344,6 +347,7 @@ struct index_state {
 	struct untracked_cache *untracked;
 	void *mmap;
 	size_t mmap_size;
+	char *last_update;
 };
 
 extern struct index_state the_index;
diff --git a/dir.h b/dir.h
index 3ec3fb0..3d540de 100644
--- a/dir.h
+++ b/dir.h
@@ -142,6 +142,9 @@ struct untracked_cache {
 	int gitignore_invalidated;
 	int dir_invalidated;
 	int dir_opened;
+	/* watchman invalidation data */
+	unsigned int use_watchman : 1;
+	struct string_list invalid_untracked;
 };
 
 struct dir_struct {
diff --git a/read-cache.c b/read-cache.c
index fe73828..6d5e871 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -19,6 +19,7 @@
 #include "split-index.h"
 #include "utf8.h"
 #include "shm.h"
+#include "ewah/ewok.h"
 
 static struct cache_entry *refresh_cache_entry(struct cache_entry *ce,
 					       unsigned int options);
@@ -41,11 +42,13 @@ static struct cache_entry *refresh_cache_entry(struct cache_entry *ce,
 #define CACHE_EXT_RESOLVE_UNDO 0x52455543 /* "REUC" */
 #define CACHE_EXT_LINK 0x6c696e6b	  /* "link" */
 #define CACHE_EXT_UNTRACKED 0x554E5452	  /* "UNTR" */
+#define CACHE_EXT_WATCHMAN 0x57414D41	  /* "WAMA" */
 
 /* changes that can be kept in $GIT_DIR/index (basically all extensions) */
 #define EXTMASK (RESOLVE_UNDO_CHANGED | CACHE_TREE_CHANGED | \
 		 CE_ENTRY_ADDED | CE_ENTRY_REMOVED | CE_ENTRY_CHANGED | \
-		 SPLIT_INDEX_ORDERED | UNTRACKED_CHANGED)
+		 SPLIT_INDEX_ORDERED | UNTRACKED_CHANGED | \
+		 WATCHMAN_CHANGED)
 
 struct index_state the_index;
 static const char *alternate_index_output;
@@ -1220,8 +1223,13 @@ int refresh_index(struct index_state *istate, unsigned int flags,
 			continue;
 
 		new = refresh_cache_ent(istate, ce, options, &cache_errno, &changed);
-		if (new == ce)
+		if (new == ce) {
+			if (ce->ce_flags & CE_WATCHMAN_DIRTY) {
+				ce->ce_flags          &= ~CE_WATCHMAN_DIRTY;
+				istate->cache_changed |= WATCHMAN_CHANGED;
+			}
 			continue;
+		}
 		if (!new) {
 			const char *fmt;
 
@@ -1365,6 +1373,94 @@ static int verify_hdr(const struct cache_header *hdr, unsigned long size)
 	return 0;
 }
 
+static void mark_no_watchman(size_t pos, void *data)
+{
+	struct index_state *istate = data;
+	assert(pos < istate->cache_nr);
+	istate->cache[pos]->ce_flags |= CE_WATCHMAN_DIRTY;
+}
+
+static int read_watchman_ext(struct index_state *istate, const void *data,
+			     unsigned long sz)
+{
+	struct ewah_bitmap *bitmap;
+	int ret, len;
+	uint32_t bitmap_size;
+	uint32_t untracked_nr;
+
+	if (memchr(data, 0, sz) == NULL)
+		return error("invalid extension");
+
+	len = strlen(data) + 1;
+	memcpy(&bitmap_size, (const char *)data + len, 4);
+	memcpy(&untracked_nr, (const char *)data + len + 4, 4);
+	untracked_nr = ntohl(untracked_nr);
+	bitmap_size = ntohl(bitmap_size);
+
+	bitmap = ewah_new();
+	ret = ewah_read_mmap(bitmap, (const char *)data + len + 8, bitmap_size);
+	if (ret != bitmap_size) {
+		ewah_free(bitmap);
+		return error("failed to parse ewah bitmap reading watchman index extension");
+	}
+	istate->last_update = xstrdup(data);
+	ewah_each_bit(bitmap, mark_no_watchman, istate);
+	ewah_free(bitmap);
+
+	/*
+	 * TODO: update the untracked cache from the untracked data in this
+	 * extension.
+	 */
+	return 0;
+}
+
+static int untracked_entry_append(struct string_list_item *item, void *sbvoid)
+{
+	struct strbuf *sb = sbvoid;
+
+	strbuf_addstr(sb, item->string);
+	strbuf_addch(sb, 0);
+	return 0;
+}
+
+void write_watchman_ext(struct strbuf *sb, struct index_state* istate)
+{
+	struct ewah_bitmap *bitmap;
+	int i;
+	int ewah_start;
+	int ewah_size = 0;
+	int fixup = 0;
+
+	strbuf_add(sb, istate->last_update, strlen(istate->last_update) + 1);
+	fixup = sb->len;
+	strbuf_add(sb, &ewah_size, 4); /* we'll fix this up later */
+	if (istate->untracked) {
+		uint32_t nr = istate->untracked->invalid_untracked.nr;
+		nr = htonl(nr);
+		strbuf_add(sb, &nr, 4);
+	} else {
+		/* zero */
+		strbuf_add(sb, &ewah_size, 4);
+	}
+
+	ewah_start = sb->len;
+	bitmap = ewah_new();
+	for (i = 0; i < istate->cache_nr; i++)
+		if (istate->cache[i]->ce_flags & CE_WATCHMAN_DIRTY)
+			ewah_set(bitmap, i);
+	ewah_serialize_strbuf(bitmap, sb);
+	ewah_free(bitmap);
+
+	/* fix up size field */
+	ewah_size = sb->len - ewah_start;
+	ewah_size = htonl(ewah_size);
+	memcpy(sb->buf + fixup, &ewah_size, 4);
+
+	if (istate->untracked)
+		for_each_string_list(&istate->untracked->invalid_untracked,
+				     untracked_entry_append, sb);
+}
+
 static int read_index_extension(struct index_state *istate,
 				const char *ext, void *data, unsigned long sz)
 {
@@ -1382,6 +1478,11 @@ static int read_index_extension(struct index_state *istate,
 	case CACHE_EXT_UNTRACKED:
 		istate->untracked = read_untracked_extension(data, sz);
 		break;
+
+	case CACHE_EXT_WATCHMAN:
+		read_watchman_ext(istate, data, sz);
+		break;
+
 	default:
 		if (*ext < 'A' || 'Z' < *ext)
 			return error("index uses %.4s extension, which we do not understand",
@@ -1791,6 +1892,8 @@ int discard_index(struct index_state *istate)
 	istate->untracked = NULL;
 	istate->from_shm = 0;
 	istate->to_shm   = 0;
+	free(istate->last_update);
+	istate->last_update = NULL;
 	return 0;
 }
 
@@ -2188,6 +2291,16 @@ static int do_write_index(struct index_state *istate, int newfd,
 		if (err)
 			return -1;
 	}
+	if (!strip_extensions && istate->last_update) {
+		struct strbuf sb = STRBUF_INIT;
+
+		write_watchman_ext(&sb, istate);
+		err = write_index_ext_header(&c, newfd, CACHE_EXT_WATCHMAN, sb.len) < 0
+			|| ce_write(&c, newfd, sb.buf, sb.len) < 0;
+		strbuf_release(&sb);
+		if (err)
+			return -1;
+	}
 
 	if (ce_flush(&c, newfd, istate->sha1) || fstat(newfd, &st))
 		return -1;

-- 
2.4.2.767.g62658d5-twtrsrc
Previous: Duy NguyenNext: David Turner
Message 11 of 25 in “index-helper, watchman”
  1. 00/15 index-helper, watchmanDavid Turner, Mar 19, 2016
  2. 01/17 read-cache.c: fix constness of verify_hdr()David Turner, Mar 19, 2016
  3. 02/17 read-cache: allow to keep mmap'd memory after readingDavid Turner, Mar 19, 2016
  4. 03/17 index-helper: new daemon for caching index and related stuffDavid Turner, Mar 19, 2016
  5. Duy NguyenMar 29, 2016
  6. David TurnerMar 29, 2016
  7. 04/17 index-helper: add --strictDavid Turner, Mar 19, 2016
  8. 05/17 daemonize(): set a flag before exiting the main processDavid Turner, Mar 19, 2016
  9. 06/17 index-helper: add --detachDavid Turner, Mar 19, 2016
  10. Duy NguyenMar 29, 2016
  11. 07/17 read-cache: add watchman 'WAMA' extensionDavid Turner, Mar 19, 2016
  12. 08/17 read-cache: invalidate untracked cache data when reading WAMADavid Turner, Mar 19, 2016
  13. Duy NguyenMar 29, 2016
  14. David TurnerMar 29, 2016
  15. 09/17 Add watchman support to reduce index refresh costDavid Turner, Mar 19, 2016
  16. Jeff HostetlerMar 24, 2016
  17. David TurnerMar 24, 2016
  18. 10/17 index-helper: use watchman to avoid refreshing index with lstat()David Turner, Mar 19, 2016
  19. 11/17 update-index: enable/disable watchman supportDavid Turner, Mar 19, 2016
  20. 12/17 unpack-trees: preserve index extensionsDavid Turner, Mar 19, 2016
  21. 13/17 index-helper: kill modeDavid Turner, Mar 19, 2016
  22. 14/17 index-helper: don't run if already runningDavid Turner, Mar 19, 2016
  23. 15/17 index-helper: autorun modeDavid Turner, Mar 19, 2016
  24. 16/17 index-helper: optionally automatically runDavid Turner, Mar 19, 2016
  25. 17/17 read-cache: config for waiting for index-helperDavid Turner, Mar 19, 2016

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