When writing a new reftable stack, Git will first create the stack with
a random suffix so that concurrent updates will not try to write to the
same file. This random suffix is computed via a call to rand(3P). But we
never seed the function via srand(3P), which means that the suffix is in
fact always the same.
Fix this bug by using `git_rand()` instead, which does not need to be
initialized. While this function is likely going to be slower depending
on the platform, this slowness should not matter in practice as we only
use it when writing a new reftable stack.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When starting a transaction via `reftable_stack_init_addition()`, we
create a lockfile for the reftable stack itself which we'll write the
new list of tables to. But if we terminate abnormally e.g. via a call to
`die()`, then we do not remove the lockfile. Subsequent executions of
Git which try to modify references will thus fail with an out-of-date
error.
Fix this bug by registering the lock as a `struct tempfile`, which
ensures automatic cleanup for us.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In `reftable_stack_reload_once()` we iterate over all the tables added
to the stack in order to figure out whether any of the tables needs to
be reloaded. We use a set of buffers in this context to compute the
paths of these tables, but discard those buffers on every iteration.
This is quite wasteful given that we do not need to transfer ownership
of the allocated buffer outside of the loop.
Refactor the code to instead reuse the buffers to reduce the number of
allocations we need to do. Note that we do not have to manually reset
the buffer because `stack_filename()` does this for us already.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Whenever updating references or reflog entries in the reftable stack, we
need to add a new table to the stack, thus growing the stack's length by
one. The stack can grow to become quite long rather quickly, leading to
performance issues when trying to read records. But besides performance
issues, this can also lead to exhaustion of file descriptors very
rapidly as every single table requires a separate descriptor when
opening the stack.
While git-pack-refs(1) fixes this issue for us by merging the tables, it
runs too irregularly to keep the length of the stack within reasonable
limits. This is why the reftable stack has an auto-compaction mechanism:
`reftable_stack_add()` will call `reftable_stack_auto_compact()` after
its added the new table, which will auto-compact the stack as required.
But while this logic works alright for `reftable_stack_add()`, we do not
do the same in `reftable_addition_commit()`, which is the transactional
equivalent to the former function that allows us to write multiple
updates to the stack atomically. Consequentially, we will easily run
into file descriptor exhaustion in code paths that use many separate
transactions like e.g. non-atomic fetches.
Fix this issue by calling `reftable_stack_auto_compact()`.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
There are calls to write(3P) where we don't properly handle interrupts.
Convert them to use `write_in_full()`.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
There are calls to pread(3P) and read(3P) where we don't properly handle
interrupts. Convert them to use `pread_in_full()` and `read_in_full()`,
respectively.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Problems identified by Coverity in the reftable code have been
corrected.
* hn/reftable-coverity-fixes:
reftable: add print functions to the record types
reftable: make reftable_record a tagged union
reftable: remove outdated file reftable.c
reftable: implement record equality generically
reftable: make reftable-record.h function signatures const correct
reftable: handle null refnames in reftable_ref_record_equal
reftable: drop stray printf in readwrite_test
reftable: order unittests by complexity
reftable: all xxx_free() functions accept NULL arguments
reftable: fix resource warning
reftable: ignore remove() return value in stack_test.c
reftable: check reftable_stack_auto_compact() return value
reftable: fix resource leak blocksource.c
reftable: fix resource leak in block.c error path
reftable: fix OOB stack write in print functions
This would trigger in the unlikely event that we are compacting, and
the next available file handle is 0.
Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Create files with mode 0666, so umask works as intended. Provides an override,
which is useful to support shared repos (test t1301-shared-repo.sh).
Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
