On Thu, Mar 24 2022, Teng Long wrote: > A Git repo can be chosen to use the normal bitmap (before MIDX) and MIDX bitmap. > > I recently tried to understand this part of the MIDX implementation because I found > a bug which has been discovered and repaired in community [1]. > > I am grateful to Taylor Blau for his help and for introducing me to the testing > method according to the `git rev-list --test-bitmap <rev>`. > > In the process of understanding and troubleshooting by using this command, I found > when the execution is failed it will output a single line of > "fatal: failed to load bitmap indexes", sometimes will be more informations like > if the bitmap file is broken, the outputs maybe contain > "error: Corrupted bitmap index file (wrong header)".), but most of time are single > line output I mentioned above. So, this brings a little obstacle for debugging and > troubleshooting I think, because "failed to load bitmap indexes" can represent > to much informations (many causes like: midx config turn off, bitmap inexistence, etc.) > > Therefore, as a git repo can be chosen to use the normal bitmap (before MIDX) or > MIDX bitmap, or they can both exist and let git make the decision. I think why not add > some extra informations based on TRACE2 to help for showing the bitmap decision path > clearer and more plentiful, so when the failure occurs the user can use it to debug > around bitmap in a quicker way. > > Thanks. > > Links: > 1. https://public-inbox.org/git/cover.1638991570.git.me@xxxxxxxxxxxx/) > > Teng Long (3): > pack-bitmap.c: use "ret" in "open_midx_bitmap()" > pack-bitmap.c: add "break" statement in "open_pack_bitmap()" > bitmap: add trace outputs during open "bitmap" file > > midx.c | 2 ++ > pack-bitmap.c | 17 +++++++++++++---- > 2 files changed, 15 insertions(+), 4 deletions(-) > > Range-diff against v0: > -: ---------- > 1: 3048b4dd29 pack-bitmap.c: use "ret" in "open_midx_bitmap()" > -: ---------- > 2: 70500b6343 pack-bitmap.c: add "break" statement in "open_pack_bitmap()" > -: ---------- > 3: 9912450fc1 bitmap: add trace outputs during open "bitmap" file Was there an on-list v0 (RFC?) or is this a range-diff against nothing? Best not to include it until a v2 then. Comments: Sometimes it's better to split up patches, but I think these 3x should really be squashed together. We make incremental progress to nowhere in 1/3 and 2/3, and it all comes together in 3/3. The 1-2/3 are trivial enough that we can squash them in. We then end up with this, with my comments added: midx.c | 2 ++ pack-bitmap.c | 17 +++++++++++++---- 2 files changed, 15 insertions(+), 4 deletions(-) diff --git a/midx.c b/midx.c index 865170bad05..fda96440287 100644 --- a/midx.c +++ b/midx.c @@ -392,6 +392,8 @@ int prepare_multi_pack_index_one(struct repository *r, const char *object_dir, i struct multi_pack_index *m_search; prepare_repo_settings(r); + trace2_data_string("midx", r, "core.multipackIndex", + r->settings.core_multi_pack_index ? "true" : "false"); Weird indentation here. Also, if we think it's a good idea to log these shouldn't it be in repo_cfg_bool() in repo-settings.c, why is core.multipackIndex out of all in r->settings special? if (!r->settings.core_multi_pack_index) return 0; diff --git a/pack-bitmap.c b/pack-bitmap.c index 97909d48da3..cac8d4a978f 100644 --- a/pack-bitmap.c +++ b/pack-bitmap.c @@ -484,25 +484,34 @@ static int open_pack_bitmap(struct repository *r, assert(!bitmap_git->map); for (p = get_all_packs(r); p; p = p->next) { - if (open_pack_bitmap_1(bitmap_git, p) == 0) + if (open_pack_bitmap_1(bitmap_git, p) == 0) { Aside: If we end up changing this line anyway, it's OK to just change it to "if (!open...". ret = 0; + break; + } } + trace2_data_string("bitmap", the_repository, "open bitmap (non-midx)", + ret ? "failed" : "ok"); return ret; } static int open_midx_bitmap(struct repository *r, struct bitmap_index *bitmap_git) { + int ret = -1; struct multi_pack_index *midx; assert(!bitmap_git->map); for (midx = get_multi_pack_index(r); midx; midx = midx->next) { - if (!open_midx_bitmap_1(bitmap_git, midx)) - return 0; + if (!open_midx_bitmap_1(bitmap_git, midx)) { + ret = 0; + break; + } } - return -1; + trace2_data_string("midx", the_repository, "open bitmap (midx)", + ret ? "failed" : "ok"); + return ret; } static int open_bitmap(struct repository *r, It seems odd not to use trace2 regions for this, and to not add add this data logging open_bitmap(). I came up with this on top of this when testing this: diff --git a/pack-bitmap.c b/pack-bitmap.c index cac8d4a978f..ba71a7ea5cd 100644 --- a/pack-bitmap.c +++ b/pack-bitmap.c @@ -318,11 +318,14 @@ static int open_midx_bitmap_1(struct bitmap_index *bitmap_git, free(idx_name); - if (fd < 0) + if (fd < 0) { + /* TODO: Log trace2_data_string() here, do we care? */ return -1; + } if (fstat(fd, &st)) { close(fd); + /* TODO: Log trace2_data_string() here, do we care? */ return -1; } @@ -330,6 +333,7 @@ static int open_midx_bitmap_1(struct bitmap_index *bitmap_git, struct strbuf buf = STRBUF_INIT; get_midx_filename(&buf, midx->object_dir); /* ignore extra bitmap file; we can only handle one */ + /* NOTE: You'll already get a warning (well, "error") event due to this, and it'll be in your region */ warning("ignoring extra bitmap file: %s", buf.buf); close(fd); strbuf_release(&buf); @@ -344,9 +348,11 @@ static int open_midx_bitmap_1(struct bitmap_index *bitmap_git, close(fd); if (load_bitmap_header(bitmap_git) < 0) + /* TODO: Add trace2_data_string() or warning/error here? */ goto cleanup; if (!hasheq(get_midx_checksum(bitmap_git->midx), bitmap_git->checksum)) + /* TODO: Add trace2_data_string() or warning/error here? */ goto cleanup; if (load_midx_revindex(bitmap_git->midx) < 0) { @@ -479,49 +485,44 @@ static int open_pack_bitmap(struct repository *r, struct bitmap_index *bitmap_git) { struct packed_git *p; - int ret = -1; - - assert(!bitmap_git->map); for (p = get_all_packs(r); p; p = p->next) { if (open_pack_bitmap_1(bitmap_git, p) == 0) { - ret = 0; - break; + return 0; } } - - trace2_data_string("bitmap", the_repository, "open bitmap (non-midx)", - ret ? "failed" : "ok"); - return ret; + return -1; } static int open_midx_bitmap(struct repository *r, struct bitmap_index *bitmap_git) { - int ret = -1; struct multi_pack_index *midx; - assert(!bitmap_git->map); - for (midx = get_multi_pack_index(r); midx; midx = midx->next) { if (!open_midx_bitmap_1(bitmap_git, midx)) { - ret = 0; - break; + return 0; } } - trace2_data_string("midx", the_repository, "open bitmap (midx)", - ret ? "failed" : "ok"); - return ret; + return -1; } static int open_bitmap(struct repository *r, struct bitmap_index *bitmap_git) { + int ret; + assert(!bitmap_git->map); - if (!open_midx_bitmap(r, bitmap_git)) - return 0; - return open_pack_bitmap(r, bitmap_git); + trace2_region_enter("pack-bitmap", "open_bitmap", r); + if (!open_midx_bitmap(r, bitmap_git)) { + ret = 0; + goto done; + } + ret = open_pack_bitmap(r, bitmap_git); +done: + trace2_region_leave("pack-bitmap", "open_bitmap", r); + return ret; } struct bitmap_index *prepare_bitmap_git(struct repository *r) I.e. surely you just want to create a region, and if you care enough to log failure shouldn't we log that in open_midx_bitmap_1() if we care, and perhaps error() there instead of silently returning -1?
