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authorJunio C Hamano <gitster@pobox.com>2018-10-19 04:34:03 (GMT)
committerJunio C Hamano <gitster@pobox.com>2018-10-19 04:34:03 (GMT)
commite27bfaaee37c4c9d7e94f945f82c3e452d2dc071 (patch)
treeb9714515dd504b5d4cff12f4ea53df1a879cb28c
parent340fde61bea189b87268aa20581e243deb744577 (diff)
parent77ff1127a4ca340fb9e81861a9851b0c3701bdc1 (diff)
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Merge branch 'bp/read-cache-parallel'
A new extension to the index file has been introduced, which allows the file to be read in parallel. * bp/read-cache-parallel: read-cache: load cache entries on worker threads ieot: add Index Entry Offset Table (IEOT) extension read-cache: load cache extensions on a worker thread config: add new index.threads config setting eoie: add End of Index Entry (EOIE) extension read-cache: clean up casting and byte decoding read-cache.c: optimize reading index format v4
-rw-r--r--Documentation/config.txt7
-rw-r--r--Documentation/technical/index-format.txt41
-rw-r--r--config.c18
-rw-r--r--config.h1
-rw-r--r--read-cache.c774
-rw-r--r--t/README5
-rwxr-xr-xt/t1700-split-index.sh13
7 files changed, 739 insertions, 120 deletions
diff --git a/Documentation/config.txt b/Documentation/config.txt
index f6f4c21..0ae4d70 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -2149,6 +2149,13 @@ imap::
The configuration variables in the 'imap' section are described
in linkgit:git-imap-send[1].
+index.threads::
+ Specifies the number of threads to spawn when loading the index.
+ This is meant to reduce index load time on multiprocessor machines.
+ Specifying 0 or 'true' will cause Git to auto-detect the number of
+ CPU's and set the number of threads accordingly. Specifying 1 or
+ 'false' will disable multithreading. Defaults to 'true'.
+
index.version::
Specify the version with which new index files should be
initialized. This does not affect existing repositories.
diff --git a/Documentation/technical/index-format.txt b/Documentation/technical/index-format.txt
index db35726..7c4d67a 100644
--- a/Documentation/technical/index-format.txt
+++ b/Documentation/technical/index-format.txt
@@ -314,3 +314,44 @@ The remaining data of each directory block is grouped by type:
- An ewah bitmap, the n-th bit indicates whether the n-th index entry
is not CE_FSMONITOR_VALID.
+
+== End of Index Entry
+
+ The End of Index Entry (EOIE) is used to locate the end of the variable
+ length index entries and the begining of the extensions. Code can take
+ advantage of this to quickly locate the index extensions without having
+ to parse through all of the index entries.
+
+ Because it must be able to be loaded before the variable length cache
+ entries and other index extensions, this extension must be written last.
+ The signature for this extension is { 'E', 'O', 'I', 'E' }.
+
+ The extension consists of:
+
+ - 32-bit offset to the end of the index entries
+
+ - 160-bit SHA-1 over the extension types and their sizes (but not
+ their contents). E.g. if we have "TREE" extension that is N-bytes
+ long, "REUC" extension that is M-bytes long, followed by "EOIE",
+ then the hash would be:
+
+ SHA-1("TREE" + <binary representation of N> +
+ "REUC" + <binary representation of M>)
+
+== Index Entry Offset Table
+
+ The Index Entry Offset Table (IEOT) is used to help address the CPU
+ cost of loading the index by enabling multi-threading the process of
+ converting cache entries from the on-disk format to the in-memory format.
+ The signature for this extension is { 'I', 'E', 'O', 'T' }.
+
+ The extension consists of:
+
+ - 32-bit version (currently 1)
+
+ - A number of index offset entries each consisting of:
+
+ - 32-bit offset from the begining of the file to the first cache entry
+ in this block of entries.
+
+ - 32-bit count of cache entries in this block
diff --git a/config.c b/config.c
index 3555c63..4051e38 100644
--- a/config.c
+++ b/config.c
@@ -2289,6 +2289,24 @@ int git_config_get_fsmonitor(void)
return 0;
}
+int git_config_get_index_threads(void)
+{
+ int is_bool, val = 0;
+
+ val = git_env_ulong("GIT_TEST_INDEX_THREADS", 0);
+ if (val)
+ return val;
+
+ if (!git_config_get_bool_or_int("index.threads", &is_bool, &val)) {
+ if (is_bool)
+ return val ? 0 : 1;
+ else
+ return val;
+ }
+
+ return 0; /* auto */
+}
+
NORETURN
void git_die_config_linenr(const char *key, const char *filename, int linenr)
{
diff --git a/config.h b/config.h
index ab46e01..a06027e 100644
--- a/config.h
+++ b/config.h
@@ -250,6 +250,7 @@ extern int git_config_get_untracked_cache(void);
extern int git_config_get_split_index(void);
extern int git_config_get_max_percent_split_change(void);
extern int git_config_get_fsmonitor(void);
+extern int git_config_get_index_threads(void);
/* This dies if the configured or default date is in the future */
extern int git_config_get_expiry(const char *key, const char **output);
diff --git a/read-cache.c b/read-cache.c
index 01859b7..4c994e4 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -23,6 +23,7 @@
#include "split-index.h"
#include "utf8.h"
#include "fsmonitor.h"
+#include "thread-utils.h"
/* Mask for the name length in ce_flags in the on-disk index */
@@ -43,6 +44,8 @@
#define CACHE_EXT_LINK 0x6c696e6b /* "link" */
#define CACHE_EXT_UNTRACKED 0x554E5452 /* "UNTR" */
#define CACHE_EXT_FSMONITOR 0x46534D4E /* "FSMN" */
+#define CACHE_EXT_ENDOFINDEXENTRIES 0x454F4945 /* "EOIE" */
+#define CACHE_EXT_INDEXENTRYOFFSETTABLE 0x49454F54 /* "IEOT" */
/* changes that can be kept in $GIT_DIR/index (basically all extensions) */
#define EXTMASK (RESOLVE_UNDO_CHANGED | CACHE_TREE_CHANGED | \
@@ -1654,7 +1657,7 @@ int verify_index_checksum;
/* Allow fsck to force verification of the cache entry order. */
int verify_ce_order;
-static int verify_hdr(struct cache_header *hdr, unsigned long size)
+static int verify_hdr(const struct cache_header *hdr, unsigned long size)
{
git_hash_ctx c;
unsigned char hash[GIT_MAX_RAWSZ];
@@ -1678,7 +1681,7 @@ static int verify_hdr(struct cache_header *hdr, unsigned long size)
}
static int read_index_extension(struct index_state *istate,
- const char *ext, void *data, unsigned long sz)
+ const char *ext, const char *data, unsigned long sz)
{
switch (CACHE_EXT(ext)) {
case CACHE_EXT_TREE:
@@ -1697,6 +1700,10 @@ static int read_index_extension(struct index_state *istate,
case CACHE_EXT_FSMONITOR:
read_fsmonitor_extension(istate, data, sz);
break;
+ case CACHE_EXT_ENDOFINDEXENTRIES:
+ case CACHE_EXT_INDEXENTRYOFFSETTABLE:
+ /* already handled in do_read_index() */
+ break;
default:
if (*ext < 'A' || 'Z' < *ext)
return error("index uses %.4s extension, which we do not understand",
@@ -1717,63 +1724,25 @@ int read_index(struct index_state *istate)
return read_index_from(istate, get_index_file(), get_git_dir());
}
-static struct cache_entry *cache_entry_from_ondisk(struct mem_pool *mem_pool,
- struct ondisk_cache_entry *ondisk,
- unsigned int flags,
- const char *name,
- size_t len)
-{
- struct cache_entry *ce = mem_pool__ce_alloc(mem_pool, len);
-
- ce->ce_stat_data.sd_ctime.sec = get_be32(&ondisk->ctime.sec);
- ce->ce_stat_data.sd_mtime.sec = get_be32(&ondisk->mtime.sec);
- ce->ce_stat_data.sd_ctime.nsec = get_be32(&ondisk->ctime.nsec);
- ce->ce_stat_data.sd_mtime.nsec = get_be32(&ondisk->mtime.nsec);
- ce->ce_stat_data.sd_dev = get_be32(&ondisk->dev);
- ce->ce_stat_data.sd_ino = get_be32(&ondisk->ino);
- ce->ce_mode = get_be32(&ondisk->mode);
- ce->ce_stat_data.sd_uid = get_be32(&ondisk->uid);
- ce->ce_stat_data.sd_gid = get_be32(&ondisk->gid);
- ce->ce_stat_data.sd_size = get_be32(&ondisk->size);
- ce->ce_flags = flags & ~CE_NAMEMASK;
- ce->ce_namelen = len;
- ce->index = 0;
- hashcpy(ce->oid.hash, ondisk->sha1);
- memcpy(ce->name, name, len);
- ce->name[len] = '\0';
- return ce;
-}
-
-/*
- * Adjacent cache entries tend to share the leading paths, so it makes
- * sense to only store the differences in later entries. In the v4
- * on-disk format of the index, each on-disk cache entry stores the
- * number of bytes to be stripped from the end of the previous name,
- * and the bytes to append to the result, to come up with its name.
- */
-static unsigned long expand_name_field(struct strbuf *name, const char *cp_)
-{
- const unsigned char *ep, *cp = (const unsigned char *)cp_;
- size_t len = decode_varint(&cp);
-
- if (name->len < len)
- die("malformed name field in the index");
- strbuf_remove(name, name->len - len, len);
- for (ep = cp; *ep; ep++)
- ; /* find the end */
- strbuf_add(name, cp, ep - cp);
- return (const char *)ep + 1 - cp_;
-}
-
-static struct cache_entry *create_from_disk(struct mem_pool *mem_pool,
+static struct cache_entry *create_from_disk(struct mem_pool *ce_mem_pool,
+ unsigned int version,
struct ondisk_cache_entry *ondisk,
unsigned long *ent_size,
- struct strbuf *previous_name)
+ const struct cache_entry *previous_ce)
{
struct cache_entry *ce;
size_t len;
const char *name;
unsigned int flags;
+ size_t copy_len;
+ /*
+ * Adjacent cache entries tend to share the leading paths, so it makes
+ * sense to only store the differences in later entries. In the v4
+ * on-disk format of the index, each on-disk cache entry stores the
+ * number of bytes to be stripped from the end of the previous name,
+ * and the bytes to append to the result, to come up with its name.
+ */
+ int expand_name_field = version == 4;
/* On-disk flags are just 16 bits */
flags = get_be16(&ondisk->flags);
@@ -1793,21 +1762,55 @@ static struct cache_entry *create_from_disk(struct mem_pool *mem_pool,
else
name = ondisk->name;
- if (!previous_name) {
- /* v3 and earlier */
- if (len == CE_NAMEMASK)
- len = strlen(name);
- ce = cache_entry_from_ondisk(mem_pool, ondisk, flags, name, len);
+ if (expand_name_field) {
+ const unsigned char *cp = (const unsigned char *)name;
+ size_t strip_len, previous_len;
+
+ /* If we're at the begining of a block, ignore the previous name */
+ strip_len = decode_varint(&cp);
+ if (previous_ce) {
+ previous_len = previous_ce->ce_namelen;
+ if (previous_len < strip_len)
+ die(_("malformed name field in the index, near path '%s'"),
+ previous_ce->name);
+ copy_len = previous_len - strip_len;
+ } else {
+ copy_len = 0;
+ }
+ name = (const char *)cp;
+ }
- *ent_size = ondisk_ce_size(ce);
- } else {
- unsigned long consumed;
- consumed = expand_name_field(previous_name, name);
- ce = cache_entry_from_ondisk(mem_pool, ondisk, flags,
- previous_name->buf,
- previous_name->len);
+ if (len == CE_NAMEMASK) {
+ len = strlen(name);
+ if (expand_name_field)
+ len += copy_len;
+ }
- *ent_size = (name - ((char *)ondisk)) + consumed;
+ ce = mem_pool__ce_alloc(ce_mem_pool, len);
+
+ ce->ce_stat_data.sd_ctime.sec = get_be32(&ondisk->ctime.sec);
+ ce->ce_stat_data.sd_mtime.sec = get_be32(&ondisk->mtime.sec);
+ ce->ce_stat_data.sd_ctime.nsec = get_be32(&ondisk->ctime.nsec);
+ ce->ce_stat_data.sd_mtime.nsec = get_be32(&ondisk->mtime.nsec);
+ ce->ce_stat_data.sd_dev = get_be32(&ondisk->dev);
+ ce->ce_stat_data.sd_ino = get_be32(&ondisk->ino);
+ ce->ce_mode = get_be32(&ondisk->mode);
+ ce->ce_stat_data.sd_uid = get_be32(&ondisk->uid);
+ ce->ce_stat_data.sd_gid = get_be32(&ondisk->gid);
+ ce->ce_stat_data.sd_size = get_be32(&ondisk->size);
+ ce->ce_flags = flags & ~CE_NAMEMASK;
+ ce->ce_namelen = len;
+ ce->index = 0;
+ hashcpy(ce->oid.hash, ondisk->sha1);
+
+ if (expand_name_field) {
+ if (copy_len)
+ memcpy(ce->name, previous_ce->name, copy_len);
+ memcpy(ce->name + copy_len, name, len + 1 - copy_len);
+ *ent_size = (name - ((char *)ondisk)) + len + 1 - copy_len;
+ } else {
+ memcpy(ce->name, name, len + 1);
+ *ent_size = ondisk_ce_size(ce);
}
return ce;
}
@@ -1893,16 +1896,237 @@ static size_t estimate_cache_size(size_t ondisk_size, unsigned int entries)
return ondisk_size + entries * per_entry;
}
+struct index_entry_offset
+{
+ /* starting byte offset into index file, count of index entries in this block */
+ int offset, nr;
+};
+
+struct index_entry_offset_table
+{
+ int nr;
+ struct index_entry_offset entries[FLEX_ARRAY];
+};
+
+#ifndef NO_PTHREADS
+static struct index_entry_offset_table *read_ieot_extension(const char *mmap, size_t mmap_size, size_t offset);
+static void write_ieot_extension(struct strbuf *sb, struct index_entry_offset_table *ieot);
+#endif
+
+static size_t read_eoie_extension(const char *mmap, size_t mmap_size);
+static void write_eoie_extension(struct strbuf *sb, git_hash_ctx *eoie_context, size_t offset);
+
+struct load_index_extensions
+{
+#ifndef NO_PTHREADS
+ pthread_t pthread;
+#endif
+ struct index_state *istate;
+ const char *mmap;
+ size_t mmap_size;
+ unsigned long src_offset;
+};
+
+static void *load_index_extensions(void *_data)
+{
+ struct load_index_extensions *p = _data;
+ unsigned long src_offset = p->src_offset;
+
+ while (src_offset <= p->mmap_size - the_hash_algo->rawsz - 8) {
+ /* After an array of active_nr index entries,
+ * there can be arbitrary number of extended
+ * sections, each of which is prefixed with
+ * extension name (4-byte) and section length
+ * in 4-byte network byte order.
+ */
+ uint32_t extsize = get_be32(p->mmap + src_offset + 4);
+ if (read_index_extension(p->istate,
+ p->mmap + src_offset,
+ p->mmap + src_offset + 8,
+ extsize) < 0) {
+ munmap((void *)p->mmap, p->mmap_size);
+ die(_("index file corrupt"));
+ }
+ src_offset += 8;
+ src_offset += extsize;
+ }
+
+ return NULL;
+}
+
+/*
+ * A helper function that will load the specified range of cache entries
+ * from the memory mapped file and add them to the given index.
+ */
+static unsigned long load_cache_entry_block(struct index_state *istate,
+ struct mem_pool *ce_mem_pool, int offset, int nr, const char *mmap,
+ unsigned long start_offset, const struct cache_entry *previous_ce)
+{
+ int i;
+ unsigned long src_offset = start_offset;
+
+ for (i = offset; i < offset + nr; i++) {
+ struct ondisk_cache_entry *disk_ce;
+ struct cache_entry *ce;
+ unsigned long consumed;
+
+ disk_ce = (struct ondisk_cache_entry *)(mmap + src_offset);
+ ce = create_from_disk(ce_mem_pool, istate->version, disk_ce, &consumed, previous_ce);
+ set_index_entry(istate, i, ce);
+
+ src_offset += consumed;
+ previous_ce = ce;
+ }
+ return src_offset - start_offset;
+}
+
+static unsigned long load_all_cache_entries(struct index_state *istate,
+ const char *mmap, size_t mmap_size, unsigned long src_offset)
+{
+ unsigned long consumed;
+
+ if (istate->version == 4) {
+ mem_pool_init(&istate->ce_mem_pool,
+ estimate_cache_size_from_compressed(istate->cache_nr));
+ } else {
+ mem_pool_init(&istate->ce_mem_pool,
+ estimate_cache_size(mmap_size, istate->cache_nr));
+ }
+
+ consumed = load_cache_entry_block(istate, istate->ce_mem_pool,
+ 0, istate->cache_nr, mmap, src_offset, NULL);
+ return consumed;
+}
+
+#ifndef NO_PTHREADS
+
+/*
+ * Mostly randomly chosen maximum thread counts: we
+ * cap the parallelism to online_cpus() threads, and we want
+ * to have at least 10000 cache entries per thread for it to
+ * be worth starting a thread.
+ */
+
+#define THREAD_COST (10000)
+
+struct load_cache_entries_thread_data
+{
+ pthread_t pthread;
+ struct index_state *istate;
+ struct mem_pool *ce_mem_pool;
+ int offset;
+ const char *mmap;
+ struct index_entry_offset_table *ieot;
+ int ieot_start; /* starting index into the ieot array */
+ int ieot_blocks; /* count of ieot entries to process */
+ unsigned long consumed; /* return # of bytes in index file processed */
+};
+
+/*
+ * A thread proc to run the load_cache_entries() computation
+ * across multiple background threads.
+ */
+static void *load_cache_entries_thread(void *_data)
+{
+ struct load_cache_entries_thread_data *p = _data;
+ int i;
+
+ /* iterate across all ieot blocks assigned to this thread */
+ for (i = p->ieot_start; i < p->ieot_start + p->ieot_blocks; i++) {
+ p->consumed += load_cache_entry_block(p->istate, p->ce_mem_pool,
+ p->offset, p->ieot->entries[i].nr, p->mmap, p->ieot->entries[i].offset, NULL);
+ p->offset += p->ieot->entries[i].nr;
+ }
+ return NULL;
+}
+
+static unsigned long load_cache_entries_threaded(struct index_state *istate, const char *mmap, size_t mmap_size,
+ unsigned long src_offset, int nr_threads, struct index_entry_offset_table *ieot)
+{
+ int i, offset, ieot_blocks, ieot_start, err;
+ struct load_cache_entries_thread_data *data;
+ unsigned long consumed = 0;
+
+ /* a little sanity checking */
+ if (istate->name_hash_initialized)
+ BUG("the name hash isn't thread safe");
+
+ mem_pool_init(&istate->ce_mem_pool, 0);
+
+ /* ensure we have no more threads than we have blocks to process */
+ if (nr_threads > ieot->nr)
+ nr_threads = ieot->nr;
+ data = xcalloc(nr_threads, sizeof(*data));
+
+ offset = ieot_start = 0;
+ ieot_blocks = DIV_ROUND_UP(ieot->nr, nr_threads);
+ for (i = 0; i < nr_threads; i++) {
+ struct load_cache_entries_thread_data *p = &data[i];
+ int nr, j;
+
+ if (ieot_start + ieot_blocks > ieot->nr)
+ ieot_blocks = ieot->nr - ieot_start;
+
+ p->istate = istate;
+ p->offset = offset;
+ p->mmap = mmap;
+ p->ieot = ieot;
+ p->ieot_start = ieot_start;
+ p->ieot_blocks = ieot_blocks;
+
+ /* create a mem_pool for each thread */
+ nr = 0;
+ for (j = p->ieot_start; j < p->ieot_start + p->ieot_blocks; j++)
+ nr += p->ieot->entries[j].nr;
+ if (istate->version == 4) {
+ mem_pool_init(&p->ce_mem_pool,
+ estimate_cache_size_from_compressed(nr));
+ } else {
+ mem_pool_init(&p->ce_mem_pool,
+ estimate_cache_size(mmap_size, nr));
+ }
+
+ err = pthread_create(&p->pthread, NULL, load_cache_entries_thread, p);
+ if (err)
+ die(_("unable to create load_cache_entries thread: %s"), strerror(err));
+
+ /* increment by the number of cache entries in the ieot block being processed */
+ for (j = 0; j < ieot_blocks; j++)
+ offset += ieot->entries[ieot_start + j].nr;
+ ieot_start += ieot_blocks;
+ }
+
+ for (i = 0; i < nr_threads; i++) {
+ struct load_cache_entries_thread_data *p = &data[i];
+
+ err = pthread_join(p->pthread, NULL);
+ if (err)
+ die(_("unable to join load_cache_entries thread: %s"), strerror(err));
+ mem_pool_combine(istate->ce_mem_pool, p->ce_mem_pool);
+ consumed += p->consumed;
+ }
+
+ free(data);
+
+ return consumed;
+}
+#endif
+
/* remember to discard_cache() before reading a different cache! */
int do_read_index(struct index_state *istate, const char *path, int must_exist)
{
- int fd, i;
+ int fd;
struct stat st;
unsigned long src_offset;
- struct cache_header *hdr;
- void *mmap;
+ const struct cache_header *hdr;
+ const char *mmap;
size_t mmap_size;
- struct strbuf previous_name_buf = STRBUF_INIT, *previous_name;
+ struct load_index_extensions p;
+ size_t extension_offset = 0;
+#ifndef NO_PTHREADS
+ int nr_threads, cpus;
+ struct index_entry_offset_table *ieot = NULL;
+#endif
if (istate->initialized)
return istate->cache_nr;
@@ -1928,7 +2152,7 @@ int do_read_index(struct index_state *istate, const char *path, int must_exist)
die_errno("unable to map index file");
close(fd);
- hdr = mmap;
+ hdr = (const struct cache_header *)mmap;
if (verify_hdr(hdr, mmap_size) < 0)
goto unmap;
@@ -1939,55 +2163,74 @@ int do_read_index(struct index_state *istate, const char *path, int must_exist)
istate->cache = xcalloc(istate->cache_alloc, sizeof(*istate->cache));
istate->initialized = 1;
- if (istate->version == 4) {
- previous_name = &previous_name_buf;
- mem_pool_init(&istate->ce_mem_pool,
- estimate_cache_size_from_compressed(istate->cache_nr));
- } else {
- previous_name = NULL;
- mem_pool_init(&istate->ce_mem_pool,
- estimate_cache_size(mmap_size, istate->cache_nr));
- }
+ p.istate = istate;
+ p.mmap = mmap;
+ p.mmap_size = mmap_size;
src_offset = sizeof(*hdr);
- for (i = 0; i < istate->cache_nr; i++) {
- struct ondisk_cache_entry *disk_ce;
- struct cache_entry *ce;
- unsigned long consumed;
- disk_ce = (struct ondisk_cache_entry *)((char *)mmap + src_offset);
- ce = create_from_disk(istate->ce_mem_pool, disk_ce, &consumed, previous_name);
- set_index_entry(istate, i, ce);
+#ifndef NO_PTHREADS
+ nr_threads = git_config_get_index_threads();
- src_offset += consumed;
+ /* TODO: does creating more threads than cores help? */
+ if (!nr_threads) {
+ nr_threads = istate->cache_nr / THREAD_COST;
+ cpus = online_cpus();
+ if (nr_threads > cpus)
+ nr_threads = cpus;
}
- strbuf_release(&previous_name_buf);
+
+ if (nr_threads > 1) {
+ extension_offset = read_eoie_extension(mmap, mmap_size);
+ if (extension_offset) {
+ int err;
+
+ p.src_offset = extension_offset;
+ err = pthread_create(&p.pthread, NULL, load_index_extensions, &p);
+ if (err)
+ die(_("unable to create load_index_extensions thread: %s"), strerror(err));
+
+ nr_threads--;
+ }
+ }
+
+ /*
+ * Locate and read the index entry offset table so that we can use it
+ * to multi-thread the reading of the cache entries.
+ */
+ if (extension_offset && nr_threads > 1)
+ ieot = read_ieot_extension(mmap, mmap_size, extension_offset);
+
+ if (ieot) {
+ src_offset += load_cache_entries_threaded(istate, mmap, mmap_size, src_offset, nr_threads, ieot);
+ free(ieot);
+ } else {
+ src_offset += load_all_cache_entries(istate, mmap, mmap_size, src_offset);
+ }
+#else
+ src_offset += load_all_cache_entries(istate, mmap, mmap_size, src_offset);
+#endif
+
istate->timestamp.sec = st.st_mtime;
istate->timestamp.nsec = ST_MTIME_NSEC(st);
- while (src_offset <= mmap_size - the_hash_algo->rawsz - 8) {
- /* After an array of active_nr index entries,
- * there can be arbitrary number of extended
- * sections, each of which is prefixed with
- * extension name (4-byte) and section length
- * in 4-byte network byte order.
- */
- uint32_t extsize;
- memcpy(&extsize, (char *)mmap + src_offset + 4, 4);
- extsize = ntohl(extsize);
- if (read_index_extension(istate,
- (const char *) mmap + src_offset,
- (char *) mmap + src_offset + 8,
- extsize) < 0)
- goto unmap;
- src_offset += 8;
- src_offset += extsize;
+ /* if we created a thread, join it otherwise load the extensions on the primary thread */
+#ifndef NO_PTHREADS
+ if (extension_offset) {
+ int ret = pthread_join(p.pthread, NULL);
+ if (ret)
+ die(_("unable to join load_index_extensions thread: %s"), strerror(ret));
+ }
+#endif
+ if (!extension_offset) {
+ p.src_offset = src_offset;
+ load_index_extensions(&p);
}
- munmap(mmap, mmap_size);
+ munmap((void *)mmap, mmap_size);
return istate->cache_nr;
unmap:
- munmap(mmap, mmap_size);
+ munmap((void *)mmap, mmap_size);
die("index file corrupt");
}
@@ -2203,11 +2446,15 @@ static int ce_write(git_hash_ctx *context, int fd, void *data, unsigned int len)
return 0;
}
-static int write_index_ext_header(git_hash_ctx *context, int fd,
- unsigned int ext, unsigned int sz)
+static int write_index_ext_header(git_hash_ctx *context, git_hash_ctx *eoie_context,
+ int fd, unsigned int ext, unsigned int sz)
{
ext = htonl(ext);
sz = htonl(sz);
+ if (eoie_context) {
+ the_hash_algo->update_fn(eoie_context, &ext, 4);
+ the_hash_algo->update_fn(eoie_context, &sz, 4);
+ }
return ((ce_write(context, fd, &ext, 4) < 0) ||
(ce_write(context, fd, &sz, 4) < 0)) ? -1 : 0;
}
@@ -2451,7 +2698,7 @@ static int do_write_index(struct index_state *istate, struct tempfile *tempfile,
{
uint64_t start = getnanotime();
int newfd = tempfile->fd;
- git_hash_ctx c;
+ git_hash_ctx c, eoie_c;
struct cache_header hdr;
int i, err = 0, removed, extended, hdr_version;
struct cache_entry **cache = istate->cache;
@@ -2460,6 +2707,10 @@ static int do_write_index(struct index_state *istate, struct tempfile *tempfile,
struct ondisk_cache_entry_extended ondisk;
struct strbuf previous_name_buf = STRBUF_INIT, *previous_name;
int drop_cache_tree = istate->drop_cache_tree;
+ off_t offset;
+ int ieot_entries = 1;
+ struct index_entry_offset_table *ieot = NULL;
+ int nr, nr_threads;
for (i = removed = extended = 0; i < entries; i++) {
if (cache[i]->ce_flags & CE_REMOVE)
@@ -2493,6 +2744,46 @@ static int do_write_index(struct index_state *istate, struct tempfile *tempfile,
if (ce_write(&c, newfd, &hdr, sizeof(hdr)) < 0)
return -1;
+#ifndef NO_PTHREADS
+ nr_threads = git_config_get_index_threads();
+ if (nr_threads != 1) {
+ int ieot_blocks, cpus;
+
+ /*
+ * ensure default number of ieot blocks maps evenly to the
+ * default number of threads that will process them leaving
+ * room for the thread to load the index extensions.
+ */
+ if (!nr_threads) {
+ ieot_blocks = istate->cache_nr / THREAD_COST;
+ cpus = online_cpus();
+ if (ieot_blocks > cpus - 1)
+ ieot_blocks = cpus - 1;
+ } else {
+ ieot_blocks = nr_threads;
+ if (ieot_blocks > istate->cache_nr)
+ ieot_blocks = istate->cache_nr;
+ }
+
+ /*
+ * no reason to write out the IEOT extension if we don't
+ * have enough blocks to utilize multi-threading
+ */
+ if (ieot_blocks > 1) {
+ ieot = xcalloc(1, sizeof(struct index_entry_offset_table)
+ + (ieot_blocks * sizeof(struct index_entry_offset)));
+ ieot_entries = DIV_ROUND_UP(entries, ieot_blocks);
+ }
+ }
+#endif
+
+ offset = lseek(newfd, 0, SEEK_CUR);
+ if (offset < 0) {
+ free(ieot);
+ return -1;
+ }
+ offset += write_buffer_len;
+ nr = 0;
previous_name = (hdr_version == 4) ? &previous_name_buf : NULL;
for (i = 0; i < entries; i++) {
@@ -2514,23 +2805,79 @@ static int do_write_index(struct index_state *istate, struct tempfile *tempfile,
drop_cache_tree = 1;
}
+ if (ieot && i && (i % ieot_entries == 0)) {
+ ieot->entries[ieot->nr].nr = nr;
+ ieot->entries[ieot->nr].offset = offset;
+ ieot->nr++;
+ /*
+ * If we have a V4 index, set the first byte to an invalid
+ * character to ensure there is nothing common with the previous
+ * entry
+ */
+ if (previous_name)
+ previous_name->buf[0] = 0;
+ nr = 0;
+ offset = lseek(newfd, 0, SEEK_CUR);
+ if (offset < 0) {
+ free(ieot);
+ return -1;
+ }
+ offset += write_buffer_len;
+ }
if (ce_write_entry(&c, newfd, ce, previous_name, (struct ondisk_cache_entry *)&ondisk) < 0)
err = -1;
if (err)
break;
+ nr++;
+ }
+ if (ieot && nr) {
+ ieot->entries[ieot->nr].nr = nr;
+ ieot->entries[ieot->nr].offset = offset;
+ ieot->nr++;
}
strbuf_release(&previous_name_buf);
- if (err)
+ if (err) {
+ free(ieot);
return err;
+ }
/* Write extension data here */
+ offset = lseek(newfd, 0, SEEK_CUR);
+ if (offset < 0) {
+ free(ieot);
+ return -1;
+ }
+ offset += write_buffer_len;
+ the_hash_algo->init_fn(&eoie_c);
+
+ /*
+ * Lets write out CACHE_EXT_INDEXENTRYOFFSETTABLE first so that we
+ * can minimize the number of extensions we have to scan through to
+ * find it during load. Write it out regardless of the
+ * strip_extensions parameter as we need it when loading the shared
+ * index.
+ */
+#ifndef NO_PTHREADS
+ if (ieot) {
+ struct strbuf sb = STRBUF_INIT;
+
+ write_ieot_extension(&sb, ieot);
+ err = write_index_ext_header(&c, &eoie_c, newfd, CACHE_EXT_INDEXENTRYOFFSETTABLE, sb.len) < 0
+ || ce_write(&c, newfd, sb.buf, sb.len) < 0;
+ strbuf_release(&sb);
+ free(ieot);
+ if (err)
+ return -1;
+ }
+#endif
+
if (!strip_extensions && istate->split_index) {
struct strbuf sb = STRBUF_INIT;
err = write_link_extension(&sb, istate) < 0 ||
- write_index_ext_header(&c, newfd, CACHE_EXT_LINK,
+ write_index_ext_header(&c, &eoie_c, newfd, CACHE_EXT_LINK,
sb.len) < 0 ||
ce_write(&c, newfd, sb.buf, sb.len) < 0;
strbuf_release(&sb);
@@ -2541,7 +2888,7 @@ static int do_write_index(struct index_state *istate, struct tempfile *tempfile,
struct strbuf sb = STRBUF_INIT;
cache_tree_write(&sb, istate->cache_tree);
- err = write_index_ext_header(&c, newfd, CACHE_EXT_TREE, sb.len) < 0
+ err = write_index_ext_header(&c, &eoie_c, newfd, CACHE_EXT_TREE, sb.len) < 0
|| ce_write(&c, newfd, sb.buf, sb.len) < 0;
strbuf_release(&sb);
if (err)
@@ -2551,7 +2898,7 @@ static int do_write_index(struct index_state *istate, struct tempfile *tempfile,
struct strbuf sb = STRBUF_INIT;
resolve_undo_write(&sb, istate->resolve_undo);
- err = write_index_ext_header(&c, newfd, CACHE_EXT_RESOLVE_UNDO,
+ err = write_index_ext_header(&c, &eoie_c, newfd, CACHE_EXT_RESOLVE_UNDO,
sb.len) < 0
|| ce_write(&c, newfd, sb.buf, sb.len) < 0;
strbuf_release(&sb);
@@ -2562,7 +2909,7 @@ static int do_write_index(struct index_state *istate, struct tempfile *tempfile,
struct strbuf sb = STRBUF_INIT;
write_untracked_extension(&sb, istate->untracked);
- err = write_index_ext_header(&c, newfd, CACHE_EXT_UNTRACKED,
+ err = write_index_ext_header(&c, &eoie_c, newfd, CACHE_EXT_UNTRACKED,
sb.len) < 0 ||
ce_write(&c, newfd, sb.buf, sb.len) < 0;
strbuf_release(&sb);
@@ -2573,7 +2920,24 @@ static int do_write_index(struct index_state *istate, struct tempfile *tempfile,
struct strbuf sb = STRBUF_INIT;
write_fsmonitor_extension(&sb, istate);
- err = write_index_ext_header(&c, newfd, CACHE_EXT_FSMONITOR, sb.len) < 0
+ err = write_index_ext_header(&c, &eoie_c, newfd, CACHE_EXT_FSMONITOR, sb.len) < 0
+ || ce_write(&c, newfd, sb.buf, sb.len) < 0;
+ strbuf_release(&sb);
+ if (err)
+ return -1;
+ }
+
+ /*
+ * CACHE_EXT_ENDOFINDEXENTRIES must be written as the last entry before the SHA1
+ * so that it can be found and processed before all the index entries are
+ * read. Write it out regardless of the strip_extensions parameter as we need it
+ * when loading the shared index.
+ */
+ if (offset) {
+ struct strbuf sb = STRBUF_INIT;
+
+ write_eoie_extension(&sb, &eoie_c, offset);
+ err = write_index_ext_header(&c, NULL, newfd, CACHE_EXT_ENDOFINDEXENTRIES, sb.len) < 0
|| ce_write(&c, newfd, sb.buf, sb.len) < 0;
strbuf_release(&sb);
if (err)
@@ -2989,3 +3353,181 @@ int should_validate_cache_entries(void)
return validate_index_cache_entries;
}
+
+#define EOIE_SIZE (4 + GIT_SHA1_RAWSZ) /* <4-byte offset> + <20-byte hash> */
+#define EOIE_SIZE_WITH_HEADER (4 + 4 + EOIE_SIZE) /* <4-byte signature> + <4-byte length> + EOIE_SIZE */
+
+static size_t read_eoie_extension(const char *mmap, size_t mmap_size)
+{
+ /*
+ * The end of index entries (EOIE) extension is guaranteed to be last
+ * so that it can be found by scanning backwards from the EOF.
+ *
+ * "EOIE"
+ * <4-byte length>
+ * <4-byte offset>
+ * <20-byte hash>
+ */
+ const char *index, *eoie;
+ uint32_t extsize;
+ size_t offset, src_offset;
+ unsigned char hash[GIT_MAX_RAWSZ];
+ git_hash_ctx c;
+
+ /* ensure we have an index big enough to contain an EOIE extension */
+ if (mmap_size < sizeof(struct cache_header) + EOIE_SIZE_WITH_HEADER + the_hash_algo->rawsz)
+ return 0;
+
+ /* validate the extension signature */
+ index = eoie = mmap + mmap_size - EOIE_SIZE_WITH_HEADER - the_hash_algo->rawsz;
+ if (CACHE_EXT(index) != CACHE_EXT_ENDOFINDEXENTRIES)
+ return 0;
+ index += sizeof(uint32_t);
+
+ /* validate the extension size */
+ extsize = get_be32(index);
+ if (extsize != EOIE_SIZE)
+ return 0;
+ index += sizeof(uint32_t);
+
+ /*
+ * Validate the offset we're going to look for the first extension
+ * signature is after the index header and before the eoie extension.
+ */
+ offset = get_be32(index);
+ if (mmap + offset < mmap + sizeof(struct cache_header))
+ return 0;
+ if (mmap + offset >= eoie)
+ return 0;
+ index += sizeof(uint32_t);
+
+ /*
+ * The hash is computed over extension types and their sizes (but not
+ * their contents). E.g. if we have "TREE" extension that is N-bytes
+ * long, "REUC" extension that is M-bytes long, followed by "EOIE",
+ * then the hash would be:
+ *
+ * SHA-1("TREE" + <binary representation of N> +
+ * "REUC" + <binary representation of M>)
+ */
+ src_offset = offset;
+ the_hash_algo->init_fn(&c);
+ while (src_offset < mmap_size - the_hash_algo->rawsz - EOIE_SIZE_WITH_HEADER) {
+ /* After an array of active_nr index entries,
+ * there can be arbitrary number of extended
+ * sections, each of which is prefixed with
+ * extension name (4-byte) and section length
+ * in 4-byte network byte order.
+ */
+ uint32_t extsize;
+ memcpy(&extsize, mmap + src_offset + 4, 4);
+ extsize = ntohl(extsize);
+
+ /* verify the extension size isn't so large it will wrap around */
+ if (src_offset + 8 + extsize < src_offset)
+ return 0;
+
+ the_hash_algo->update_fn(&c, mmap + src_offset, 8);
+
+ src_offset += 8;
+ src_offset += extsize;
+ }
+ the_hash_algo->final_fn(hash, &c);
+ if (!hasheq(hash, (const unsigned char *)index))
+ return 0;
+
+ /* Validate that the extension offsets returned us back to the eoie extension. */
+ if (src_offset != mmap_size - the_hash_algo->rawsz - EOIE_SIZE_WITH_HEADER)
+ return 0;
+
+ return offset;
+}
+
+static void write_eoie_extension(struct strbuf *sb, git_hash_ctx *eoie_context, size_t offset)
+{
+ uint32_t buffer;
+ unsigned char hash[GIT_MAX_RAWSZ];
+
+ /* offset */
+ put_be32(&buffer, offset);
+ strbuf_add(sb, &buffer, sizeof(uint32_t));
+
+ /* hash */
+ the_hash_algo->final_fn(hash, eoie_context);
+ strbuf_add(sb, hash, the_hash_algo->rawsz);
+}
+
+#ifndef NO_PTHREADS
+#define IEOT_VERSION (1)
+
+static struct index_entry_offset_table *read_ieot_extension(const char *mmap, size_t mmap_size, size_t offset)
+{
+ const char *index = NULL;
+ uint32_t extsize, ext_version;
+ struct index_entry_offset_table *ieot;
+ int i, nr;
+
+ /* find the IEOT extension */
+ if (!offset)
+ return NULL;
+ while (offset <= mmap_size - the_hash_algo->rawsz - 8) {
+ extsize = get_be32(mmap + offset + 4);
+ if (CACHE_EXT((mmap + offset)) == CACHE_EXT_INDEXENTRYOFFSETTABLE) {
+ index = mmap + offset + 4 + 4;
+ break;
+ }
+ offset += 8;
+ offset += extsize;
+ }
+ if (!index)
+ return NULL;
+
+ /* validate the version is IEOT_VERSION */
+ ext_version = get_be32(index);
+ if (ext_version != IEOT_VERSION) {
+ error("invalid IEOT version %d", ext_version);
+ return NULL;
+ }
+ index += sizeof(uint32_t);
+
+ /* extension size - version bytes / bytes per entry */
+ nr = (extsize - sizeof(uint32_t)) / (sizeof(uint32_t) + sizeof(uint32_t));
+ if (!nr) {
+ error("invalid number of IEOT entries %d", nr);
+ return NULL;
+ }
+ ieot = xmalloc(sizeof(struct index_entry_offset_table)
+ + (nr * sizeof(struct index_entry_offset)));
+ ieot->nr = nr;
+ for (i = 0; i < nr; i++) {
+ ieot->entries[i].offset = get_be32(index);
+ index += sizeof(uint32_t);
+ ieot->entries[i].nr = get_be32(index);
+ index += sizeof(uint32_t);
+ }
+
+ return ieot;
+}
+
+static void write_ieot_extension(struct strbuf *sb, struct index_entry_offset_table *ieot)
+{
+ uint32_t buffer;
+ int i;
+
+ /* version */
+ put_be32(&buffer, IEOT_VERSION);
+ strbuf_add(sb, &buffer, sizeof(uint32_t));
+
+ /* ieot */
+ for (i = 0; i < ieot->nr; i++) {
+
+ /* offset */
+ put_be32(&buffer, ieot->entries[i].offset);
+ strbuf_add(sb, &buffer, sizeof(uint32_t));
+
+ /* count */
+ put_be32(&buffer, ieot->entries[i].nr);
+ strbuf_add(sb, &buffer, sizeof(uint32_t));
+ }
+}
+#endif
diff --git a/t/README b/t/README
index d8b04c3..8847489 100644
--- a/t/README
+++ b/t/README
@@ -338,6 +338,11 @@ for the index version specified. Can be set to any valid version
GIT_TEST_PRELOAD_INDEX=<boolean> exercises the preload-index code path
by overriding the minimum number of cache entries required per thread.
+GIT_TEST_INDEX_THREADS=<n> enables exercising the multi-threaded loading
+of the index for the whole test suite by bypassing the default number of
+cache entries and thread minimums. Setting this to 1 will make the
+index loading single threaded.
+
Naming Tests
------------
diff --git a/t/t1700-split-index.sh b/t/t1700-split-index.sh
index 8f8807d..3e618ca 100755
--- a/t/t1700-split-index.sh
+++ b/t/t1700-split-index.sh
@@ -6,7 +6,12 @@ test_description='split index mode tests'
# We need total control of index splitting here
sane_unset GIT_TEST_SPLIT_INDEX
+
+# Testing a hard coded SHA against an index with an extension
+# that can vary from run to run is problematic so we disable
+# those extensions.
sane_unset GIT_TEST_FSMONITOR
+sane_unset GIT_TEST_INDEX_THREADS
test_expect_success 'enable split index' '
git config splitIndex.maxPercentChange 100 &&
@@ -15,11 +20,11 @@ test_expect_success 'enable split index' '
indexversion=$(test-tool index-version <.git/index) &&
if test "$indexversion" = "4"
then
- own=432ef4b63f32193984f339431fd50ca796493569
- base=508851a7f0dfa8691e9f69c7f055865389012491
+ own=3527df833c6c100d3d1d921a9a782d62a8be4b58
+ base=746f7ab2ed44fb839efdfbffcf399d0b113fb4cb
else
- own=8299b0bcd1ac364e5f1d7768efb62fa2da79a339
- base=39d890139ee5356c7ef572216cebcd27aa41f9df
+ own=5e9b60117ece18da410ddecc8b8d43766a0e4204
+ base=4370042739b31cd17a5c5cd6043a77c9a00df113
fi &&
cat >expect <<-EOF &&
own $own