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Wed, 19 Aug 2026 06:20:05 -0700 (PDT) Received: from [127.0.0.2] ([2a02:8109:d906:4e00:15a6:881d:7fd4:eabb]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-499a9ddee1esm37578955e9.2.2026.08.19.06.20.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 19 Aug 2026 06:20:04 -0700 (PDT) From: Karthik Nayak Date: Wed, 19 Aug 2026 15:19:38 +0200 Subject: [PATCH 2/3] reftable/stack: move list lock to `struct reftable_stack` Precedence: bulk X-Mailing-List: git@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260819-740-optimize-reloading-the-reftable-stack-v1-2-6bf5305d4e43@gmail.com> References: <20260819-740-optimize-reloading-the-reftable-stack-v1-0-6bf5305d4e43@gmail.com> In-Reply-To: <20260819-740-optimize-reloading-the-reftable-stack-v1-0-6bf5305d4e43@gmail.com> To: git@vger.kernel.org Cc: Karthik Nayak X-Mailer: b4 0.15.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=3685; i=karthik.188@gmail.com; h=from:subject:message-id; bh=g48qNFzXKAjUoPXUG/7RmHIP2neHN4nWPNVmz1DC96Q=; b=owJ4nAHtARL+kA0DAAoBPtWfJI5GjH8ByyZiAGqFrYCpSHg88T34Q+4Yc4u6to0r2VE+36zt2 dI+jSG2aPCKPYkBswQAAQoAHRYhBFfOTH9jdXEPy2XGBj7VnySORox/BQJqha2AAAoJED7VnySO Rox/F3ML/RwKf9bM6RpRRWxO8hiIMhhNAfrSJ833lMCm8R5Kzm/gka+7TjAYoqm+CMjsA8LBoCL 9mWoG4F0WeoeokcIiYlb2NHmXeJ4Hs+1mKsaqrQE3RVfHHy6BHwYDb+iYWTaKUSHPn2w67amfs+ iBx8FN/G31KtFnBVpoyNUryI6Q7/lmzk3wcmLNRu0tEC/iYVZUUnCl/nDLre5ZGnsci+MC9M3x5 ZLb7NFTuq5vpl48T0kP3XjFjjXOxOMq5dMeUdgHxusbKKuTwfWwIen2TWiWl2Z4eLmvcBWvG5dJ mB+24IjeHb81Wcd+fBfP2M3C83eSzZQxxjpEpLYhYWr77jjwXO19kTjn7jkDfH5xJiYrNkF1J3X f0ymV+PX2pakM9asVNcXIEcHsShMxYT7Bu29nKxDlpQ72p9qwx9ttj9WXkCYFBjj5K99GludK+p 171bnOCoIUzyZp5dro8g63IZODTtcrz3nR6+LX1pK3gyi7QgTL4GY8Cljs/iBOhoeh2Fv4VMKr9 SY= X-Developer-Key: i=karthik.188@gmail.com; a=openpgp; fpr=57CE4C7F6375710FCB65C6063ED59F248E468C7F The struct `reftable_addition` is used to modify a given stack, as such, it also includes a `struct reftable_flock` used to obtain the lock to the list file. While the scope of the field lies within this struct, it doesn't allow for optimizations to be made on `struct reftable_stack` itself. Move the field to `struct reftable_stack`, allowing us to make a simple optimization around avoiding a stack reload when we have already obtained a lock. While this is currently possible in the write path, the write path also contains multiple branches to reads which only work on top of `struct reftable_stack`, and we would miss the optimization in such paths. While here, remove an unused header file from 'reftable/stack.h'. Signed-off-by: Karthik Nayak --- reftable/stack.c | 15 ++++++++------- reftable/stack.h | 7 ++++++- 2 files changed, 14 insertions(+), 8 deletions(-) diff --git a/reftable/stack.c b/reftable/stack.c index 540f5e77ac..e449af9c03 100644 --- a/reftable/stack.c +++ b/reftable/stack.c @@ -536,6 +536,8 @@ int reftable_new_stack(struct reftable_stack **dest, const char *dir, goto out; } + p->list_lock = REFTABLE_FLOCK_INIT; + err = reftable_stack_reload_maybe_reuse(p, 1); if (err < 0) goto out; @@ -628,7 +630,6 @@ int reftable_stack_reload(struct reftable_stack *st) } struct reftable_addition { - struct reftable_flock tables_list_lock; struct reftable_stack *stack; struct reftable_write_options opts; @@ -653,7 +654,7 @@ static void reftable_addition_close(struct reftable_addition *add) add->new_tables_len = 0; add->new_tables_cap = 0; - flock_release(&add->tables_list_lock); + flock_release(&add->stack->list_lock); reftable_buf_release(&nm); } @@ -669,13 +670,13 @@ static int reftable_stack_init_addition(struct reftable_addition *add, if (opts) add->opts = *opts; - err = flock_acquire(&add->tables_list_lock, st->list_file, + err = flock_acquire(&add->stack->list_lock, st->list_file, add->opts.lock_timeout_ms); if (err < 0) goto done; if (add->opts.default_permissions) { - if (chmod(add->tables_list_lock.path, + if (chmod(add->stack->list_lock.path, add->opts.default_permissions) < 0) { err = REFTABLE_IO_ERROR; goto done; @@ -774,7 +775,7 @@ int reftable_addition_commit(struct reftable_addition *add) goto done; } - err = reftable_write_data(add->tables_list_lock.fd, + err = reftable_write_data(add->stack->list_lock.fd, table_list.buf, table_list.len); reftable_buf_release(&table_list); if (err < 0) { @@ -782,13 +783,13 @@ int reftable_addition_commit(struct reftable_addition *add) goto done; } - err = fsync(add->tables_list_lock.fd); + err = fsync(add->stack->list_lock.fd); if (err < 0) { err = REFTABLE_IO_ERROR; goto done; } - err = flock_commit(&add->tables_list_lock); + err = flock_commit(&add->stack->list_lock); if (err < 0) { err = REFTABLE_IO_ERROR; goto done; diff --git a/reftable/stack.h b/reftable/stack.h index f7901e6c6f..52e07ad551 100644 --- a/reftable/stack.h +++ b/reftable/stack.h @@ -10,7 +10,6 @@ #define STACK_H #include "system.h" -#include "reftable-writer.h" #include "reftable-stack.h" struct reftable_stack { @@ -18,6 +17,12 @@ struct reftable_stack { char *list_file; int list_fd; + /* + * Set while an addition holds the stack locked. Used by + * stack_uptodate() to skip reload checks while locked. + */ + struct reftable_flock list_lock; + char *reftable_dir; struct reftable_stack_options opts; -- 2.55.GIT