kernel/git - git - PowerEL Git System

Author	SHA1	Message	Date
Michael Haggerty	7c6bd25c7d	files-backend: don't rewrite the `packed-refs` file unnecessarily Even when we are deleting references, we needn't overwrite the `packed-refs` file if the references that we are deleting only exist as loose references. Implement this optimization as follows: * Add a function `is_packed_transaction_needed()`, which checks whether a given packed-refs transaction actually needs to be carried out (i.e., it returns false if the transaction obviously wouldn't have any effect). This function must be called while holding the `packed-refs` lock to avoid races. * Change `files_transaction_prepare()` to check whether the packed-refs transaction is actually needed. If not, squelch it, but continue holding the `packed-refs` lock until the end of the transaction to avoid races. This fixes a mild regression caused by `dc39e09942` (files_ref_store: use a transaction to update packed refs, 2017-09-08). Before that commit, unnecessary rewrites of `packed-refs` were suppressed by `repack_without_refs()`. But the transaction-based writing introduced by that commit didn't perform that optimization. Note that the pre-dc39e09942 code still had to read the whole `packed-refs` file to determine that the rewrite could be skipped, so the performance for the cases that the write could be elided was `O(N)` in the number of packed references both before and after `dc39e09942`. But after that commit the constant factor increased. This commit reimplements the optimization of eliding unnecessary `packed-refs` rewrites. That, plus the fact that since cfa2e29c34 (packed_ref_store: get rid of the `ref_cache` entirely, 2017-03-17) we don't necessarily have to read the whole `packed-refs` file at all, means that deletes of one or a few loose references can now be done with `O(n lg N)` effort, where `n` is the number of loose references being deleted and `N` is the total number of packed references. This commit fixes two tests in t1409. Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>	7 years ago
Michael Haggerty	9939b33d6a	packed-backend: rip out some now-unused code Now the outside world interacts with the packed ref store only via the generic refs API plus a few lock-related functions. This allows us to delete some functions that are no longer used, thereby completing the encapsulation of the packed ref store. Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>	8 years ago
Michael Haggerty	2775d8724d	packed_ref_store: implement reference transactions Implement the methods needed to support reference transactions for the packed-refs backend. The new methods are not yet used. Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>	8 years ago
Michael Haggerty	49aebcf432	packed_refs_unlock(), packed_refs_is_locked(): new functions Add two new public functions, `packed_refs_unlock()` and `packed_refs_is_locked()`, with which callers can manage and query the `packed-refs` lock externally. Call `packed_refs_unlock()` from `commit_packed_refs()` and `rollback_packed_refs()`. Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>	8 years ago
Michael Haggerty	c8bed835c2	packed_refs_lock(): report errors via a `struct strbuf *err` That way the callers don't have to come up with error messages themselves. Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>	8 years ago
Michael Haggerty	b7de57d8d1	packed_refs_lock(): function renamed from lock_packed_refs() Rename `lock_packed_refs()` to `packed_refs_lock()` for consistency with how other methods are named. Also, it's about to get some companions. Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>	8 years ago
Michael Haggerty	3478983b51	commit_packed_refs(): report errors rather than dying Report errors via a `struct strbuf *err` rather than by calling `die()`. To enable this goal, change `write_packed_entry()` to report errors via a return value and `errno` rather than dying. Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>	8 years ago
Michael Haggerty	e0cc8ac820	packed_ref_store: make class into a subclass of `ref_store` Add the infrastructure to make `packed_ref_store` implement `ref_store`, at least formally (few of the methods are actually implemented yet). Change the functions in its interface to take `ref_store ` arguments. Change `files_ref_store` to store a pointer to `ref_store ` and to call functions via the virtual `ref_store` interface where possible. This also means that a few `packed_ref_store` functions can become static. This is a work in progress. Some more `ref_store` methods will soon be implemented (e.g., those having to do with reference transactions). But some of them will never be implemented (e.g., those having to do with symrefs or reflogs). Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>	8 years ago
Michael Haggerty	67be7c5a59	packed-backend: new module for handling packed references Now that the interface between `files_ref_store` and `packed_ref_store` is relatively narrow, move the latter into a new module, "refs/packed-backend.h" and "refs/packed-backend.c". It still doesn't quite implement the `ref_store` interface, but it will soon. This commit moves code around and adjusts its visibility, but doesn't change anything. Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>	8 years ago