reftable/stack: stop using `fsync_component()` directly

We're executing `fsync_component()` directly in the reftable library so
that we can fsync data to disk depending on "core.fsync". But as we're
in the process of converting the reftable library to become standalone
we cannot use that function in the library anymore.

Refactor the code such that users of the library can inject a custom
fsync function via the write options. This allows us to get rid of the
dependency on "write-or-die.h".

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/refs/reftable-backend.c b/refs/reftable-backend.c
index 7d86d920970e7c34e8f921311becf5da22ccddaf..2e774176eda3b2c112b6145acdd9dc60db0a62d2 100644 (file)
--- a/refs/reftable-backend.c
+++ b/refs/reftable-backend.c
@@ -24,6 +24,7 @@
 #include "../setup.h"
 #include "../strmap.h"
 #include "../trace2.h"
+#include "../write-or-die.h"
 #include "parse.h"
 #include "refs-internal.h"
 
@@ -273,6 +274,11 @@ static int reftable_be_config(const char *var, const char *value,
        return 0;
 }
 
+static int reftable_be_fsync(int fd)
+{
+       return fsync_component(FSYNC_COMPONENT_REFERENCE, fd);
+}
+
 static struct ref_store *reftable_be_init(struct repository *repo,
                                          const char *gitdir,
                                          unsigned int store_flags)
@@ -304,6 +310,7 @@ static struct ref_store *reftable_be_init(struct repository *repo,
        refs->write_options.disable_auto_compact =
                !git_env_bool("GIT_TEST_REFTABLE_AUTOCOMPACTION", 1);
        refs->write_options.lock_timeout_ms = 100;
+       refs->write_options.fsync = reftable_be_fsync;
 
        git_config(reftable_be_config, &refs->write_options);
 

diff --git a/reftable/reftable-writer.h b/reftable/reftable-writer.h
index 211860d08a4aac50d81f66d67ac81610aa941412..c85ef5a5bd14595d75f99457fef4407040e197c5 100644 (file)
--- a/reftable/reftable-writer.h
+++ b/reftable/reftable-writer.h
@@ -62,6 +62,12 @@ struct reftable_write_options {
         * negative value will cause us to block indefinitely.
         */
        long lock_timeout_ms;
+
+       /*
+        * Optional callback used to fsync files to disk. Falls back to using
+        * fsync(3P) when unset.
+        */
+       int (*fsync)(int fd);
 };
 
 /* reftable_block_stats holds statistics for a single block type */

diff --git a/reftable/stack.c b/reftable/stack.c
index 9ae716ff375f8ee311e766142f02c9a47d8b140c..c67bdd952cac780c9b7e38eb490186af375eb337 100644 (file)
--- a/reftable/stack.c
+++ b/reftable/stack.c
@@ -8,7 +8,6 @@ https://developers.google.com/open-source/licenses/bsd
 
 #include "stack.h"
 
-#include "../write-or-die.h"
 #include "system.h"
 #include "constants.h"
 #include "merged.h"
@@ -43,17 +42,28 @@ static int stack_filename(struct reftable_buf *dest, struct reftable_stack *st,
        return 0;
 }
 
-static ssize_t reftable_fd_write(void *arg, const void *data, size_t sz)
+static int stack_fsync(const struct reftable_write_options *opts, int fd)
 {
-       int *fdp = (int *)arg;
-       return write_in_full(*fdp, data, sz);
+       if (opts->fsync)
+               return opts->fsync(fd);
+       return fsync(fd);
 }
 
-static int reftable_fd_flush(void *arg)
+struct fd_writer {
+       const struct reftable_write_options *opts;
+       int fd;
+};
+
+static ssize_t fd_writer_write(void *arg, const void *data, size_t sz)
 {
-       int *fdp = (int *)arg;
+       struct fd_writer *writer = arg;
+       return write_in_full(writer->fd, data, sz);
+}
 
-       return fsync_component(FSYNC_COMPONENT_REFERENCE, *fdp);
+static int fd_writer_flush(void *arg)
+{
+       struct fd_writer *writer = arg;
+       return stack_fsync(writer->opts, writer->fd);
 }
 
 int reftable_new_stack(struct reftable_stack **dest, const char *dir,
@@ -765,7 +775,7 @@ int reftable_addition_commit(struct reftable_addition *add)
                goto done;
        }
 
-       err = fsync_component(FSYNC_COMPONENT_REFERENCE, lock_file_fd);
+       err = stack_fsync(&add->stack->opts, lock_file_fd);
        if (err < 0) {
                err = REFTABLE_IO_ERROR;
                goto done;
@@ -858,8 +868,10 @@ int reftable_addition_add(struct reftable_addition *add,
        struct reftable_buf next_name = REFTABLE_BUF_INIT;
        struct reftable_writer *wr = NULL;
        struct tempfile *tab_file = NULL;
+       struct fd_writer writer = {
+               .opts = &add->stack->opts,
+       };
        int err = 0;
-       int tab_fd;
 
        reftable_buf_reset(&next_name);
 
@@ -887,10 +899,10 @@ int reftable_addition_add(struct reftable_addition *add,
                        goto done;
                }
        }
-       tab_fd = get_tempfile_fd(tab_file);
 
-       err = reftable_writer_new(&wr, reftable_fd_write, reftable_fd_flush,
-                                 &tab_fd, &add->stack->opts);
+       writer.fd = get_tempfile_fd(tab_file);
+       err = reftable_writer_new(&wr, fd_writer_write, fd_writer_flush,
+                                 &writer, &add->stack->opts);
        if (err < 0)
                goto done;
 
@@ -973,8 +985,11 @@ static int stack_compact_locked(struct reftable_stack *st,
        struct reftable_buf next_name = REFTABLE_BUF_INIT;
        struct reftable_buf tab_file_path = REFTABLE_BUF_INIT;
        struct reftable_writer *wr = NULL;
+       struct fd_writer writer=  {
+               .opts = &st->opts,
+       };
        struct tempfile *tab_file;
-       int tab_fd, err = 0;
+       int err = 0;
 
        err = format_name(&next_name, reftable_reader_min_update_index(st->readers[first]),
                          reftable_reader_max_update_index(st->readers[last]));
@@ -994,7 +1009,6 @@ static int stack_compact_locked(struct reftable_stack *st,
                err = REFTABLE_IO_ERROR;
                goto done;
        }
-       tab_fd = get_tempfile_fd(tab_file);
 
        if (st->opts.default_permissions &&
            chmod(get_tempfile_path(tab_file), st->opts.default_permissions) < 0) {
@@ -1002,8 +1016,9 @@ static int stack_compact_locked(struct reftable_stack *st,
                goto done;
        }
 
-       err = reftable_writer_new(&wr, reftable_fd_write, reftable_fd_flush,
-                                 &tab_fd, &st->opts);
+       writer.fd = get_tempfile_fd(tab_file);
+       err = reftable_writer_new(&wr, fd_writer_write, fd_writer_flush,
+                                 &writer, &st->opts);
        if (err < 0)
                goto done;
 
@@ -1460,7 +1475,7 @@ static int stack_compact_range(struct reftable_stack *st,
                goto done;
        }
 
-       err = fsync_component(FSYNC_COMPONENT_REFERENCE, get_lock_file_fd(&tables_list_lock));
+       err = stack_fsync(&st->opts, get_lock_file_fd(&tables_list_lock));
        if (err < 0) {
                err = REFTABLE_IO_ERROR;
                unlink(new_table_path.buf);