git/trace.c, branch v2.0.2

shallow.c: the 8 steps to select new commits for .git/shallow

2013-12-11T00:14:16Z

Suppose a fetch or push is requested between two shallow repositories (with no history deepening or shortening). A pack that contains necessary objects is transferred over together with .git/shallow of the sender. The receiver has to determine whether it needs to update .git/shallow if new refs needs new shallow comits. The rule here is avoid updating .git/shallow by default. But we don't want to waste the received pack. If the pack contains two refs, one needs new shallow commits installed in .git/shallow and one does not, we keep the latter and reject/warn about the former. Even if .git/shallow update is allowed, we only add shallow commits strictly necessary for the former ref (remember the sender can send more shallow commits than necessary) and pay attention not to accidentally cut the receiver history short (no history shortening is asked for) So the steps to figure out what ref need what new shallow commits are: 1. Split the sender shallow commit list into "ours" and "theirs" list by has_sha1_file. Those that exist in current repo in "ours", the remaining in "theirs". 2. Check the receiver .git/shallow, remove from "ours" the ones that also exist in .git/shallow. 3. Fetch the new pack. Either install or unpack it. 4. Do has_sha1_file on "theirs" list again. Drop the ones that fail has_sha1_file. Obviously the new pack does not need them. 5. If the pack is kept, remove from "ours" the ones that do not exist in the new pack. 6. Walk the new refs to answer the question "what shallow commits, both ours and theirs, are required in .git/shallow in order to add this ref?". Shallow commits not associated to any refs are removed from their respective list. 7. (*) Check reachability (from the current refs) of all remaining commits in "ours". Those reachable are removed. We do not want to cut any part of our (reachable) history. We only check up commits. True reachability test is done by check_everything_connected() at the end as usual. 8. Combine the final "ours" and "theirs" and add them all to .git/shallow. Install new refs. The case where some hook rejects some refs on a push is explained in more detail in the push patches. Of these steps, #6 and #7 are expensive. Both require walking through some commits, or in the worst case all commits. And we rather avoid them in at least common case, where the transferred pack does not contain any shallow commits that the sender advertises. Let's look at each scenario: 1) the sender has longer history than the receiver All shallow commits from the sender will be put into "theirs" list at step 1 because none of them exists in current repo. In the common case, "theirs" becomes empty at step 4 and exit early. 2) the sender has shorter history than the receiver All shallow commits from the sender are likely in "ours" list at step 1. In the common case, if the new pack is kept, we could empty "ours" and exit early at step 5. If the pack is not kept, we hit the expensive step 6 then exit after "ours" is emptied. There'll be only a handful of objects to walk in fast-forward case. If it's forced update, we may need to walk to the bottom. 3) the sender has same .git/shallow as the receiver This is similar to case 2 except that "ours" should be emptied at step 2 and exit early. A fetch after "clone --depth=X" is case 1. A fetch after "clone" (from a shallow repo) is case 3. Luckily they're cheap for the common case. A push from "clone --depth=X" falls into case 2, which is expensive. Some more work may be done at the sender/client side to avoid more work on the server side: if the transferred pack does not contain any shallow commits, send-pack should not send any shallow commits to the receive-pack, effectively turning it into a normal push and avoid all steps. This patch implements all steps except #3, already handled by fetch-pack and receive-pack, #6 and #7, which has their own patch due to their size. (*) in previous versions step 7 was put before step 3. I reorder it so that the common case that keeps the pack does not need to walk commits at all. In future if we implement faster commit reachability check (maybe with the help of pack bitmaps or commit cache), step 7 could become cheap and be moved up before 6 again. Signed-off-by: Nguyễn Thái Ngọc Duy Signed-off-by: Junio C Hamano

add missing "format" function attributes

2013-07-10T05:23:04Z

For most of our functions that take printf-like formats, we use gcc's __attribute__((format)) to get compiler warnings when the functions are misused. Let's give a few more functions the same protection. In most cases, the annotations do not uncover any actual bugs; the only code change needed is that we passed a size_t to transfer_debug, which expected an int. Since we expect the passed-in value to be a relatively small buffer size (and cast a similar value to int directly below), we can just cast away the problem. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano

trace.c: mark a private file-scope symbol as static

2012-09-16T05:58:21Z

Signed-off-by: Junio C Hamano

Fix sparse warnings

2011-03-22T17:16:54Z

Fix warnings from 'make check'. - These files don't include 'builtin.h' causing sparse to complain that cmd_* isn't declared: builtin/clone.c:364, builtin/fetch-pack.c:797, builtin/fmt-merge-msg.c:34, builtin/hash-object.c:78, builtin/merge-index.c:69, builtin/merge-recursive.c:22 builtin/merge-tree.c:341, builtin/mktag.c:156, builtin/notes.c:426 builtin/notes.c:822, builtin/pack-redundant.c:596, builtin/pack-refs.c:10, builtin/patch-id.c:60, builtin/patch-id.c:149, builtin/remote.c:1512, builtin/remote-ext.c:240, builtin/remote-fd.c:53, builtin/reset.c:236, builtin/send-pack.c:384, builtin/unpack-file.c:25, builtin/var.c:75 - These files have symbols which should be marked static since they're only file scope: submodule.c:12, diff.c:631, replace_object.c:92, submodule.c:13, submodule.c:14, trace.c:78, transport.c:195, transport-helper.c:79, unpack-trees.c:19, url.c:3, url.c:18, url.c:104, url.c:117, url.c:123, url.c:129, url.c:136, thread-utils.c:21, thread-utils.c:48 - These files redeclare symbols to be different types: builtin/index-pack.c:210, parse-options.c:564, parse-options.c:571, usage.c:49, usage.c:58, usage.c:63, usage.c:72 - These files use a literal integer 0 when they really should use a NULL pointer: daemon.c:663, fast-import.c:2942, imap-send.c:1072, notes-merge.c:362 While we're in the area, clean up some unused #includes in builtin files (mostly exec_cmd.h). Signed-off-by: Stephen Boyd Signed-off-by: Junio C Hamano

trace: give repo_setup trace its own key

2011-03-08T20:12:04Z

You no longer get this output with GIT_TRACE=1; instead, you can do GIT_TRACE_SETUP=1. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano

trace: add trace_strbuf

2011-03-08T20:12:04Z

If you happen to have a strbuf, it is a little more readable and a little more efficient to be able to print it directly instead of jamming it through the trace_printf interface. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano

trace: factor out "do we want to trace" logic

2011-03-08T20:12:04Z

As we add more tracing areas, this will avoid repeated code. Technically, trace_printf already checks this and will avoid printing if the trace key is not set. However, callers may want to find out early whether or not tracing is enabled so they can avoid doing work in the common non-trace case. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano

trace: refactor to support multiple env variables

2011-03-08T20:12:04Z

Right now you turn all tracing off and on with GIT_TRACE. To support new types of tracing without forcing the user to see all of them, we will soon support turning each tracing area on with GIT_TRACE_*. This patch lays the groundwork by providing an interface which does not assume GIT_TRACE. However, we still maintain the trace_printf interface so that existing callers do not need to be refactored. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano

trace: add trace_vprintf

2011-03-08T20:12:04Z

This is a necessary cleanup to adding new types of trace functions. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano

strbuf: add strbuf_vaddf

2011-02-26T09:06:50Z

In a variable-args function, the code for writing into a strbuf is non-trivial. We ended up cutting and pasting it in several places because there was no vprintf-style function for strbufs (which in turn was held up by a lack of va_copy). Now that we have a fallback va_copy, we can add strbuf_vaddf, the strbuf equivalent of vsprintf. And we can clean up the cut and paste mess. Signed-off-by: Jeff King Improved-by: Christian Couder Signed-off-by: Jonathan Nieder Signed-off-by: Junio C Hamano