diff options
Diffstat (limited to 'Documentation/technical')
| -rw-r--r-- | Documentation/technical/api-trace2.txt | 44 | ||||
| -rw-r--r-- | Documentation/technical/bundle-format.txt | 11 | ||||
| -rw-r--r-- | Documentation/technical/commit-graph-format.txt | 12 | ||||
| -rw-r--r-- | Documentation/technical/multi-pack-index.txt | 1 | ||||
| -rw-r--r-- | Documentation/technical/pack-format.txt | 13 | ||||
| -rw-r--r-- | Documentation/technical/partial-clone.txt | 3 | ||||
| -rw-r--r-- | Documentation/technical/reftable.txt | 2 |
7 files changed, 52 insertions, 34 deletions
diff --git a/Documentation/technical/api-trace2.txt b/Documentation/technical/api-trace2.txt index bb13ca3db8..f4a8a69087 100644 --- a/Documentation/technical/api-trace2.txt +++ b/Documentation/technical/api-trace2.txt @@ -5,7 +5,7 @@ information to stderr or a file. The Trace2 feature is inactive unless explicitly enabled by enabling one or more Trace2 Targets. The Trace2 API is intended to replace the existing (Trace1) -printf-style tracing provided by the existing `GIT_TRACE` and +`printf()`-style tracing provided by the existing `GIT_TRACE` and `GIT_TRACE_PERFORMANCE` facilities. During initial implementation, Trace2 and Trace1 may operate in parallel. @@ -24,8 +24,8 @@ for example. Trace2 is controlled using `trace2.*` config values in the system and global config files and `GIT_TRACE2*` environment variables. Trace2 does -not read from repo local or worktree config files or respect `-c` -command line config settings. +not read from repo local or worktree config files, nor does it respect +`-c` command line config settings. == Trace2 Targets @@ -34,8 +34,8 @@ Format details are given in a later section. === The Normal Format Target -The normal format target is a tradition printf format and similar -to GIT_TRACE format. This format is enabled with the `GIT_TRACE2` +The normal format target is a traditional `printf()` format and similar +to the `GIT_TRACE` format. This format is enabled with the `GIT_TRACE2` environment variable or the `trace2.normalTarget` system or global config setting. @@ -69,8 +69,8 @@ $ cat ~/log.normal === The Performance Format Target The performance format target (PERF) is a column-based format to -replace GIT_TRACE_PERFORMANCE and is suitable for development and -testing, possibly to complement tools like gprof. This format is +replace `GIT_TRACE_PERFORMANCE` and is suitable for development and +testing, possibly to complement tools like `gprof`. This format is enabled with the `GIT_TRACE2_PERF` environment variable or the `trace2.perfTarget` system or global config setting. @@ -128,7 +128,7 @@ yields ------------ $ cat ~/log.event -{"event":"version","sid":"sid":"20190408T191610.507018Z-H9b68c35f-P000059a8","thread":"main","time":"2019-01-16T17:28:42.620713Z","file":"common-main.c","line":38,"evt":"3","exe":"2.20.1.155.g426c96fcdb"} +{"event":"version","sid":"20190408T191610.507018Z-H9b68c35f-P000059a8","thread":"main","time":"2019-01-16T17:28:42.620713Z","file":"common-main.c","line":38,"evt":"3","exe":"2.20.1.155.g426c96fcdb"} {"event":"start","sid":"20190408T191610.507018Z-H9b68c35f-P000059a8","thread":"main","time":"2019-01-16T17:28:42.621027Z","file":"common-main.c","line":39,"t_abs":0.001173,"argv":["git","version"]} {"event":"cmd_name","sid":"20190408T191610.507018Z-H9b68c35f-P000059a8","thread":"main","time":"2019-01-16T17:28:42.621122Z","file":"git.c","line":432,"name":"version","hierarchy":"version"} {"event":"exit","sid":"20190408T191610.507018Z-H9b68c35f-P000059a8","thread":"main","time":"2019-01-16T17:28:42.621236Z","file":"git.c","line":662,"t_abs":0.001227,"code":0} @@ -170,9 +170,9 @@ Some functions have a `_va_fl()` suffix to indicate that they also take a `va_list` argument. Some functions have a `_printf_fl()` suffix to indicate that they also -take a varargs argument. +take a `printf()` style format with a variable number of arguments. -There are CPP wrapper macros and ifdefs to hide most of these details. +There are CPP wrapper macros and `#ifdef`s to hide most of these details. See `trace2.h` for more details. The following discussion will only describe the simplified forms. @@ -234,7 +234,7 @@ Events are written as lines of the form: is the event name. `<event-message>`:: - is a free-form printf message intended for human consumption. + is a free-form `printf()` message intended for human consumption. + Note that this may contain embedded LF or CRLF characters that are not escaped, so the event may spill across multiple lines. @@ -300,7 +300,7 @@ This field is in anticipation of in-proc submodules in the future. indicate a broad category, such as "index" or "status". `<perf-event-message>`:: - is a free-form printf message intended for human consumption. + is a free-form `printf()` message intended for human consumption. ------------ 15:33:33.532712 wt-status.c:2310 | d0 | main | region_enter | r1 | 0.126064 | | status | label:print @@ -533,7 +533,7 @@ these special values are used: ------------ `"cmd_mode"`:: - This event, when present, describes the command variant This + This event, when present, describes the command variant. This event may be emitted more than once. + ------------ @@ -588,7 +588,7 @@ with "?". `"child_exit"`:: This event is generated after the current process has returned - from the waitpid() and collected the exit information from the + from the `waitpid()` and collected the exit information from the child. + ------------ @@ -609,7 +609,7 @@ process may be a shell script which doesn't have a session-id.) + Note that the `t_rel` field contains the observed run time in seconds for the child process (starting before the fork/exec/spawn and -stopping after the waitpid() and includes OS process creation overhead). +stopping after the `waitpid()` and includes OS process creation overhead). So this time will be slightly larger than the atexit time reported by the child process itself. @@ -635,7 +635,7 @@ process may be a shell script which doesn't have a session-id.) + This event is generated after the child is started in the background and given a little time to boot up and start working. If the child -startups normally and while the parent is still waiting, the "ready" +starts up normally while the parent is still waiting, the "ready" field will have the value "ready". If the child is too slow to start and the parent times out, the field will have the value "timeout". @@ -949,7 +949,7 @@ atexit elapsed:3.868970 code:0 Regions:: - Regions can be use to time an interesting section of code. + Regions can be used to time an interesting section of code. + ---------------- void wt_status_collect(struct wt_status *s) @@ -1103,9 +1103,9 @@ Thread Events:: Thread messages added to a thread-proc. + -For example, the multithreaded preload-index code can be +For example, the multi-threaded preload-index code can be instrumented with a region around the thread pool and then -per-thread start and exit events within the threadproc. +per-thread start and exit events within the thread-proc. + ---------------- static void *preload_thread(void *_data) @@ -1214,11 +1214,11 @@ as each thread starts and allocates TLS storage. There are a few issues to resolve before we can completely switch to Trace2. -* Updating existing tests that assume GIT_TRACE format messages. +* Updating existing tests that assume `GIT_TRACE` format messages. -* How to best handle custom GIT_TRACE_<key> messages? +* How to best handle custom `GIT_TRACE_<key>` messages? -** The GIT_TRACE_<key> mechanism allows each <key> to write to a +** The `GIT_TRACE_<key>` mechanism allows each <key> to write to a different file (in addition to just stderr). ** Do we want to maintain that ability or simply write to the existing diff --git a/Documentation/technical/bundle-format.txt b/Documentation/technical/bundle-format.txt index bac558d049..b9be8644cf 100644 --- a/Documentation/technical/bundle-format.txt +++ b/Documentation/technical/bundle-format.txt @@ -71,6 +71,11 @@ and the Git bundle v2 format cannot represent a shallow clone repository. == Capabilities Because there is no opportunity for negotiation, unknown capabilities cause 'git -bundle' to abort. The only known capability is `object-format`, which specifies -the hash algorithm in use, and can take the same values as the -`extensions.objectFormat` configuration value. +bundle' to abort. + +* `object-format` specifies the hash algorithm in use, and can take the same + values as the `extensions.objectFormat` configuration value. + +* `filter` specifies an object filter as in the `--filter` option in + linkgit:git-rev-list[1]. The resulting pack-file must be marked as a + `.promisor` pack-file after it is unbundled. diff --git a/Documentation/technical/commit-graph-format.txt b/Documentation/technical/commit-graph-format.txt index 87971c27dd..484b185ba9 100644 --- a/Documentation/technical/commit-graph-format.txt +++ b/Documentation/technical/commit-graph-format.txt @@ -93,7 +93,7 @@ CHUNK DATA: 2 bits of the lowest byte, storing the 33rd and 34th bit of the commit time. - Generation Data (ID: {'G', 'D', 'A', 'T' }) (N * 4 bytes) [Optional] + Generation Data (ID: {'G', 'D', 'A', '2' }) (N * 4 bytes) [Optional] * This list of 4-byte values store corrected commit date offsets for the commits, arranged in the same order as commit data chunk. * If the corrected commit date offset cannot be stored within 31 bits, @@ -104,7 +104,7 @@ CHUNK DATA: by compatible versions of Git and in case of split commit-graph chains, the topmost layer also has Generation Data chunk. - Generation Data Overflow (ID: {'G', 'D', 'O', 'V' }) [Optional] + Generation Data Overflow (ID: {'G', 'D', 'O', '2' }) [Optional] * This list of 8-byte values stores the corrected commit date offsets for commits with corrected commit date offsets that cannot be stored within 31 bits. @@ -156,3 +156,11 @@ CHUNK DATA: TRAILER: H-byte HASH-checksum of all of the above. + +== Historical Notes: + +The Generation Data (GDA2) and Generation Data Overflow (GDO2) chunks have +the number '2' in their chunk IDs because a previous version of Git wrote +possibly erroneous data in these chunks with the IDs "GDAT" and "GDOV". By +changing the IDs, newer versions of Git will silently ignore those older +chunks and write the new information without trusting the incorrect data. diff --git a/Documentation/technical/multi-pack-index.txt b/Documentation/technical/multi-pack-index.txt index b39c69da8c..f2221d2b44 100644 --- a/Documentation/technical/multi-pack-index.txt +++ b/Documentation/technical/multi-pack-index.txt @@ -24,6 +24,7 @@ and their offsets into multiple packfiles. It contains: ** An offset within the jth packfile for the object. * If large offsets are required, we use another list of large offsets similar to version 2 pack-indexes. +- An optional list of objects in pseudo-pack order (used with MIDX bitmaps). Thus, we can provide O(log N) lookup time for any number of packfiles. diff --git a/Documentation/technical/pack-format.txt b/Documentation/technical/pack-format.txt index 8d2f42f29e..6d3efb7d16 100644 --- a/Documentation/technical/pack-format.txt +++ b/Documentation/technical/pack-format.txt @@ -376,6 +376,11 @@ CHUNK DATA: [Optional] Object Large Offsets (ID: {'L', 'O', 'F', 'F'}) 8-byte offsets into large packfiles. + [Optional] Bitmap pack order (ID: {'R', 'I', 'D', 'X'}) + A list of MIDX positions (one per object in the MIDX, num_objects in + total, each a 4-byte unsigned integer in network byte order), sorted + according to their relative bitmap/pseudo-pack positions. + TRAILER: Index checksum of the above contents. @@ -456,9 +461,5 @@ In short, a MIDX's pseudo-pack is the de-duplicated concatenation of objects in packs stored by the MIDX, laid out in pack order, and the packs arranged in MIDX order (with the preferred pack coming first). -Finally, note that the MIDX's reverse index is not stored as a chunk in -the multi-pack-index itself. This is done because the reverse index -includes the checksum of the pack or MIDX to which it belongs, which -makes it impossible to write in the MIDX. To avoid races when rewriting -the MIDX, a MIDX reverse index includes the MIDX's checksum in its -filename (e.g., `multi-pack-index-xyz.rev`). +The MIDX's reverse index is stored in the optional 'RIDX' chunk within +the MIDX itself. diff --git a/Documentation/technical/partial-clone.txt b/Documentation/technical/partial-clone.txt index a0dd7c66f2..99f0eb3040 100644 --- a/Documentation/technical/partial-clone.txt +++ b/Documentation/technical/partial-clone.txt @@ -181,6 +181,9 @@ Fetching Missing Objects currently fetches all objects referred to by the requested objects, even though they are not necessary. +- Fetching with `--refetch` will request a complete new filtered packfile from + the remote, which can be used to change a filter without needing to + dynamically fetch missing objects. Using many promisor remotes --------------------------- diff --git a/Documentation/technical/reftable.txt b/Documentation/technical/reftable.txt index d7c3b645cf..6a67cc4174 100644 --- a/Documentation/technical/reftable.txt +++ b/Documentation/technical/reftable.txt @@ -443,7 +443,7 @@ Obj block format Object blocks are optional. Writers may choose to omit object blocks, especially if readers will not use the object name to ref mapping. -Object blocks use unique, abbreviated 2-32 object name keys, mapping to +Object blocks use unique, abbreviated 2-31 byte object name keys, mapping to ref blocks containing references pointing to that object directly, or as the peeled value of an annotated tag. Like ref blocks, object blocks use the file's standard block size. The abbreviation length is available in |