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Blame and "git log --stat" recover hunk coordinates by diffing blob pairs, and recompute them on every run. Add a cache of those coordinates at $GIT_DIR/objects/info/diff-hunks, beside the commit-graph, so a later run can look them up instead of decompressing the blobs and running xdiff again. The store is a single chunk-format file (see gitformat-chunk(5)): an 8-byte header, a DHIX index of fixed-size entries sorted by key, a DHDT segment of hunk records, and a trailing hash checksum. An entry is keyed by the two blob object ids and the xdl_opts the pair was diffed under, so a stored result is served only where that exact key recurs, independent of path. A zero-context diff trims unchanged lines from hunk edges and can pick a different but equally valid set of hunks than an untrimmed diff, so a recording caller stores a pair only when its trimmed and untrimmed diffs are identical; such an entry answers any consumer at any context, and the rare divergent pair is always computed. Identical hunk blocks are interned once and shared across keys. The library provides a reader (repo_diff_hunks_store and _replay, gated by core.diffHunks), loaded once and cached on the object database as the commit-graph is, and a writer that accumulates entries and flushes them in one atomic pass. An absent, corrupt, or disabled store reads as all misses. A record with no hunks is invalid too: replaying it would claim the pair equivalent, which the store never asserts, so it reads as a miss. Ordinary reads are diagnostic-free. Loading parses the chunk table through read_table_of_contents_quiet(), new in chunk-format, which prints nothing on a malformed table and takes the repository's hash algorithm rather than the_hash_algo, so the file is bounds-checked under the algorithm it is keyed by. The flush closes the repository's mmapped store and forgets that loading was attempted before committing the lockfile. A warming run that also reads may hold the file it is replacing mapped, and the rename must not land on a live mapping, which Windows refuses; a read after the flush then observes the committed file. commit-graph closes its graph before committing for the same reason. Writing is off by default, enabled per run by GIT_DIFF_HUNKS_WRITE or persistently by diffHunks.write, the environment winning. A writer seeds from the existing store, so a flush merges rather than replaces. The seed's checksum is verified first: a corrupt store is discarded, not rewritten with a fresh checksum verify could no longer catch. An entry that fails the shared diff_provider_check_hunk() or names no blob is dropped with a warning, since it would only ever read as a miss. A seed that discarded or dropped anything forces the flush even when the warming run computed nothing new. The writer fsyncs through a new diff-hunks core.fsync component. "git diff-hunks" inspects and manages the file: "verify" checks the checksum, chunk table, sort order, entry bounds, and every entry's hunk sequence against that shared check, so a store whose entries could only read as misses fails verify; "clear" removes the file. Later patches wire the readers and the writer into the diff and blame paths. Signed-off-by: Michael Montalbo <mmontalbo@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
221 lines
7.2 KiB
C
221 lines
7.2 KiB
C
#include "git-compat-util.h"
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#include "config.h"
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#include "repo-settings.h"
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#include "repository.h"
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#include "midx.h"
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#include "pack-objects.h"
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#include "setup.h"
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static void repo_cfg_bool(struct repository *r, const char *key, int *dest,
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int def)
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{
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if (repo_config_get_bool(r, key, dest))
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*dest = def;
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}
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static void repo_cfg_int(struct repository *r, const char *key, int *dest,
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int def)
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{
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if (repo_config_get_int(r, key, dest))
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*dest = def;
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}
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static void repo_cfg_ulong(struct repository *r, const char *key, unsigned long *dest,
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unsigned long def)
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{
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if (repo_config_get_ulong(r, key, dest))
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*dest = def;
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}
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void prepare_repo_settings(struct repository *r)
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{
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int experimental;
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int value;
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const char *strval;
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int manyfiles;
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int read_changed_paths;
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unsigned long ulongval;
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if (!r->gitdir)
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BUG("Cannot add settings for uninitialized repository");
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if (r->settings.initialized)
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return;
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repo_settings_clear(r);
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r->settings.initialized++;
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/* Booleans config or default, cascades to other settings */
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repo_cfg_bool(r, "feature.manyfiles", &manyfiles, 0);
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repo_cfg_bool(r, "feature.experimental", &experimental, 0);
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/* Defaults modified by feature.* */
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if (experimental) {
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r->settings.fetch_negotiation_algorithm = FETCH_NEGOTIATION_SKIPPING;
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r->settings.pack_use_bitmap_boundary_traversal = 1;
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r->settings.pack_use_multi_pack_reuse = 1;
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r->settings.pack_use_path_walk = 1;
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}
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if (manyfiles) {
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r->settings.index_version = 4;
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r->settings.index_skip_hash = 1;
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r->settings.core_untracked_cache = UNTRACKED_CACHE_WRITE;
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r->settings.pack_use_path_walk = 1;
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}
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/* Commit graph config or default, does not cascade (simple) */
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repo_cfg_bool(r, "core.commitgraph", &r->settings.core_commit_graph, 1);
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repo_cfg_int(r, "commitgraph.generationversion", &r->settings.commit_graph_generation_version, 2);
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repo_cfg_bool(r, "commitgraph.readchangedpaths", &read_changed_paths, 1);
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repo_cfg_int(r, "commitgraph.changedpathsversion",
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&r->settings.commit_graph_changed_paths_version,
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read_changed_paths ? -1 : 0);
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repo_cfg_bool(r, "gc.writecommitgraph", &r->settings.gc_write_commit_graph, 1);
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repo_cfg_bool(r, "fetch.writecommitgraph", &r->settings.fetch_write_commit_graph, 0);
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/* Boolean config or default, does not cascade (simple) */
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repo_cfg_bool(r, "pack.usesparse", &r->settings.pack_use_sparse, 1);
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repo_cfg_bool(r, "pack.usepathwalk", &r->settings.pack_use_path_walk, 0);
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repo_cfg_bool(r, "core.multipackindex", &r->settings.core_multi_pack_index, 1);
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repo_cfg_bool(r, "core.diffhunks", &r->settings.core_diff_hunks, 1);
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repo_cfg_bool(r, "index.sparse", &r->settings.sparse_index, 0);
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repo_cfg_bool(r, "index.skiphash", &r->settings.index_skip_hash, r->settings.index_skip_hash);
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repo_cfg_bool(r, "pack.readreverseindex", &r->settings.pack_read_reverse_index, 1);
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repo_cfg_bool(r, "pack.usebitmapboundarytraversal",
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&r->settings.pack_use_bitmap_boundary_traversal,
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r->settings.pack_use_bitmap_boundary_traversal);
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repo_cfg_bool(r, "core.usereplacerefs", &r->settings.read_replace_refs, 1);
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/*
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* The GIT_TEST_MULTI_PACK_INDEX variable is special in that
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* either it *or* the config sets
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* r->settings.core_multi_pack_index if true. We don't take
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* the environment variable if it exists (even if false) over
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* any config, as in most other cases.
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*/
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if (git_env_bool(GIT_TEST_MULTI_PACK_INDEX, 0))
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r->settings.core_multi_pack_index = 1;
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/*
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* Non-boolean config
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*/
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if (!repo_config_get_int(r, "index.version", &value))
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r->settings.index_version = value;
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repo_cfg_int(r, "core.maxtreedepth",
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&r->settings.max_allowed_tree_depth,
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DEFAULT_MAX_ALLOWED_TREE_DEPTH);
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if (!repo_config_get_string_tmp(r, "core.untrackedcache", &strval)) {
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int v = git_parse_maybe_bool(strval);
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/*
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* If it's set to "keep", or some other non-boolean
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* value then "v < 0". Then we do nothing and keep it
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* at the default of UNTRACKED_CACHE_KEEP.
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*/
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if (v >= 0)
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r->settings.core_untracked_cache = v ?
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UNTRACKED_CACHE_WRITE : UNTRACKED_CACHE_REMOVE;
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}
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if (!repo_config_get_string_tmp(r, "fetch.negotiationalgorithm", &strval)) {
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int fetch_default = r->settings.fetch_negotiation_algorithm;
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if (!strcasecmp(strval, "skipping"))
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r->settings.fetch_negotiation_algorithm = FETCH_NEGOTIATION_SKIPPING;
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else if (!strcasecmp(strval, "noop"))
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r->settings.fetch_negotiation_algorithm = FETCH_NEGOTIATION_NOOP;
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else if (!strcasecmp(strval, "consecutive"))
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r->settings.fetch_negotiation_algorithm = FETCH_NEGOTIATION_CONSECUTIVE;
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else if (!strcasecmp(strval, "default"))
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r->settings.fetch_negotiation_algorithm = fetch_default;
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else
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die("unknown fetch negotiation algorithm '%s'", strval);
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}
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/*
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* This setting guards all index reads to require a full index
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* over a sparse index. After suitable guards are placed in the
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* codebase around uses of the index, this setting will be
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* removed.
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*/
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r->settings.command_requires_full_index = 1;
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if (!repo_config_get_ulong(r, "core.deltabasecachelimit", &ulongval))
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r->settings.delta_base_cache_limit = ulongval;
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if (!repo_config_get_ulong(r, "core.packedgitwindowsize", &ulongval)) {
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int pgsz_x2 = getpagesize() * 2;
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/* This value must be multiple of (pagesize * 2) */
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ulongval /= pgsz_x2;
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if (ulongval < 1)
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ulongval = 1;
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r->settings.packed_git_window_size = ulongval * pgsz_x2;
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}
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if (!repo_config_get_ulong(r, "core.packedgitlimit", &ulongval))
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r->settings.packed_git_limit = ulongval;
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}
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void repo_settings_clear(struct repository *r)
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{
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struct repo_settings empty = REPO_SETTINGS_INIT;
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FREE_AND_NULL(r->settings.fsmonitor);
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FREE_AND_NULL(r->settings.hooks_path);
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r->settings = empty;
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}
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unsigned long repo_settings_get_big_file_threshold(struct repository *repo)
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{
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if (!repo->settings.big_file_threshold)
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repo_cfg_ulong(repo, "core.bigfilethreshold",
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&repo->settings.big_file_threshold, 512 * 1024 * 1024);
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return repo->settings.big_file_threshold;
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}
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void repo_settings_set_big_file_threshold(struct repository *repo, unsigned long value)
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{
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repo->settings.big_file_threshold = value;
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}
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int repo_settings_get_warn_ambiguous_refs(struct repository *repo)
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{
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prepare_repo_settings(repo);
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if (repo->settings.warn_ambiguous_refs < 0)
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repo_cfg_bool(repo, "core.warnambiguousrefs",
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&repo->settings.warn_ambiguous_refs, 1);
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return repo->settings.warn_ambiguous_refs;
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}
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const char *repo_settings_get_hooks_path(struct repository *repo)
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{
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if (!repo->settings.hooks_path)
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repo_config_get_pathname(repo, "core.hookspath", &repo->settings.hooks_path);
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return repo->settings.hooks_path;
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}
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int repo_settings_get_shared_repository(struct repository *repo)
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{
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if (!repo->settings.shared_repository_initialized) {
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const char *var = "core.sharedrepository";
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const char *value;
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if (!repo_config_get_value(repo, var, &value))
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repo->settings.shared_repository = git_config_perm(var, value);
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else
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repo->settings.shared_repository = PERM_UMASK;
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repo->settings.shared_repository_initialized = 1;
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}
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return repo->settings.shared_repository;
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}
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void repo_settings_set_shared_repository(struct repository *repo, int value)
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{
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repo->settings.shared_repository = value;
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repo->settings.shared_repository_initialized = 1;
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}
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void repo_settings_reset_shared_repository(struct repository *repo)
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{
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repo->settings.shared_repository_initialized = 0;
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}
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