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sd-journal: use FILE streams to buffer write_uint64()

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journal_file_verify() uses a set of tmpfs files to create lists
of object positions by type.

The existing code used a bare write() call for every object
position written, incurring a syscall per listed object.

This commit encapsulates the bare file descriptors in FILE *'s
and replaces the bare write with fwrite, buffering the writes so
there's less syscalls.

Cached `journalctl --verify` tests showed a ~8% faster runtime
with this change on a release build, verifying 1.3GiB of
production journals across 16 files.
This commit is contained in:
Vito Caputo
2021-09-02 11:29:23 +02:00
committed by Lennart Poettering
parent fad45198b6
commit a4121e965f
1 changed files with 40 additions and 24 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/libsystemd/sd-journal/journal-verify.c
+40 -24
View File
@@ -380,14 +380,9 @@ static int journal_file_object_verify(JournalFile *f, uint64_t offset, Object *o
return 0;
}
static int write_uint64(int fd, uint64_t p) {
ssize_t k;
k = write(fd, &p, sizeof(p));
if (k < 0)
static int write_uint64(FILE *fp, uint64_t p) {
if (fwrite(&p, sizeof(p), 1, fp) != 1)
return -errno;
if (k != sizeof(p))
return -EIO;
return 0;
}
@@ -843,7 +838,8 @@ int journal_file_verify(
bool entry_seqnum_set = false, entry_monotonic_set = false, entry_realtime_set = false, found_main_entry_array = false;
uint64_t n_weird = 0, n_objects = 0, n_entries = 0, n_data = 0, n_fields = 0, n_data_hash_tables = 0, n_field_hash_tables = 0, n_entry_arrays = 0, n_tags = 0;
usec_t last_usec = 0;
int data_fd = -1, entry_fd = -1, entry_array_fd = -1;
_cleanup_close_ int data_fd = -1, entry_fd = -1, entry_array_fd = -1;
_cleanup_fclose_ FILE *data_fp = NULL, *entry_fp = NULL, *entry_array_fp = NULL;
MMapFileDescriptor *cache_data_fd = NULL, *cache_entry_fd = NULL, *cache_entry_array_fd = NULL;
unsigned i;
bool found_last = false;
@@ -910,6 +906,24 @@ int journal_file_verify(
goto fail;
}
r = take_fdopen_unlocked(&data_fd, "w+", &data_fp);
if (r < 0) {
log_error_errno(r, "Failed to open data file stream: %m");
goto fail;
}
r = take_fdopen_unlocked(&entry_fd, "w+", &entry_fp);
if (r < 0) {
log_error_errno(r, "Failed to open entry file stream: %m");
goto fail;
}
r = take_fdopen_unlocked(&entry_array_fd, "w+", &entry_array_fp);
if (r < 0) {
log_error_errno(r, "Failed to open entry array file stream: %m");
goto fail;
}
if (le32toh(f->header->compatible_flags) & ~HEADER_COMPATIBLE_SUPPORTED) {
log_error("Cannot verify file with unknown extensions.");
r = -EOPNOTSUPP;
@@ -984,7 +998,7 @@ int journal_file_verify(
switch (o->object.type) {
case OBJECT_DATA:
r = write_uint64(data_fd, p);
r = write_uint64(data_fp, p);
if (r < 0)
goto fail;
@@ -1002,7 +1016,7 @@ int journal_file_verify(
goto fail;
}
r = write_uint64(entry_fd, p);
r = write_uint64(entry_fp, p);
if (r < 0)
goto fail;
@@ -1089,7 +1103,7 @@ int journal_file_verify(
break;
case OBJECT_ENTRY_ARRAY:
r = write_uint64(entry_array_fd, p);
r = write_uint64(entry_array_fp, p);
if (r < 0)
goto fail;
@@ -1279,6 +1293,21 @@ int journal_file_verify(
goto fail;
}
if (fflush(data_fp) != 0) {
r = log_error_errno(errno, "Failed to flush data file stream: %m");
goto fail;
}
if (fflush(entry_fp) != 0) {
r = log_error_errno(errno, "Failed to flush entry file stream: %m");
goto fail;
}
if (fflush(entry_array_fp) != 0) {
r = log_error_errno(errno, "Failed to flush entry array file stream: %m");
goto fail;
}
/* Second iteration: we follow all objects referenced from the
* two entry points: the object hash table and the entry
* array. We also check that everything referenced (directly
@@ -1312,10 +1341,6 @@ int journal_file_verify(
mmap_cache_free_fd(f->mmap, cache_entry_fd);
mmap_cache_free_fd(f->mmap, cache_entry_array_fd);
safe_close(data_fd);
safe_close(entry_fd);
safe_close(entry_array_fd);
if (first_contained)
*first_contained = le64toh(f->header->head_entry_realtime);
if (last_validated)
@@ -1335,15 +1360,6 @@ fail:
(unsigned long long) f->last_stat.st_size,
100 * p / f->last_stat.st_size);
if (data_fd >= 0)
safe_close(data_fd);
if (entry_fd >= 0)
safe_close(entry_fd);
if (entry_array_fd >= 0)
safe_close(entry_array_fd);
if (cache_data_fd)
mmap_cache_free_fd(f->mmap, cache_data_fd);