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shared: add vectorized parse_field() (#7056)

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By vectorizing parse_field() the chain of parse_field() calls in
output_short() can be replaced with a single call receiving a description
of the desired fields and their targets.

While at it, eliminate the repeated strlen() calls performed on constant
field names by making parse_field() receive the field length, and storing
it in the ParseFieldVec at compile time.

Also sort the output_short() fields so the short ones are tried first, for
a minor efficiency gain.

In addition to making the code less repetitive, gcc in my tests now inlines
the parse_fieldv() call in output_short().
This commit is contained in:
Vito Caputo 2017-10-11 23:14:07 -07:00 committed by Zbigniew Jędrzejewski-Szmek
parent 709dbeac14
commit ed05452014
1 changed files with 48 additions and 59 deletions
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107
src/shared/logs-show.c
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@ -79,37 +79,63 @@ static int print_catalog(FILE *f, sd_journal *j) {
return 0;
}
static int parse_field(const void *data, size_t length, const char *field, char **target, size_t *target_size) {
size_t fl, nl;
static int parse_field(const void *data, size_t length, const char *field, size_t field_len, char **target, size_t *target_len) {
size_t nl;
char *buf;
assert(data);
assert(field);
assert(target);
fl = strlen(field);
if (length < fl)
if (length < field_len)
return 0;
if (memcmp(data, field, fl))
if (memcmp(data, field, field_len))
return 0;
nl = length - fl;
nl = length - field_len;
buf = newdup_suffix0(char, (const char*) data + fl, nl);
buf = newdup_suffix0(char, (const char*) data + field_len, nl);
if (!buf)
return log_oom();
free(*target);
*target = buf;
if (target_size)
*target_size = nl;
if (target_len)
*target_len = nl;
return 1;
}
typedef struct ParseFieldVec {
const char *field;
size_t field_len;
char **target;
size_t *target_len;
} ParseFieldVec;
#define PARSE_FIELD_VEC_ENTRY(_field, _target, _target_len) \
{ .field = _field, .field_len = strlen(_field), .target = _target, .target_len = _target_len }
static int parse_fieldv(const void *data, size_t length, const ParseFieldVec *fields, unsigned n_fields) {
unsigned i;
for (i = 0; i < n_fields; i++) {
const ParseFieldVec *f = &fields[i];
int r;
r = parse_field(data, length, f->field, f->field_len, f->target, f->target_len);
if (r < 0)
return r;
else if (r > 0)
break;
}
return 0;
}
static bool shall_print(const char *p, size_t l, OutputFlags flags) {
assert(p);
@ -337,6 +363,17 @@ static int output_short(
size_t hostname_len = 0, identifier_len = 0, comm_len = 0, pid_len = 0, fake_pid_len = 0, message_len = 0, realtime_len = 0, monotonic_len = 0, priority_len = 0;
int p = LOG_INFO;
bool ellipsized = false;
const ParseFieldVec fields[] = {
PARSE_FIELD_VEC_ENTRY("_PID=", &pid, &pid_len),
PARSE_FIELD_VEC_ENTRY("_COMM=", &comm, &comm_len),
PARSE_FIELD_VEC_ENTRY("MESSAGE=", &message, &message_len),
PARSE_FIELD_VEC_ENTRY("PRIORITY=", &priority, &priority_len),
PARSE_FIELD_VEC_ENTRY("_HOSTNAME=", &hostname, &hostname_len),
PARSE_FIELD_VEC_ENTRY("SYSLOG_PID=", &fake_pid, &fake_pid_len),
PARSE_FIELD_VEC_ENTRY("SYSLOG_IDENTIFIER=", &identifier, &identifier_len),
PARSE_FIELD_VEC_ENTRY("_SOURCE_REALTIME_TIMESTAMP=", &realtime, &realtime_len),
PARSE_FIELD_VEC_ENTRY("_SOURCE_MONOTONIC_TIMESTAMP=", &monotonic, &monotonic_len),
};
assert(f);
assert(j);
@ -351,55 +388,7 @@ static int output_short(
JOURNAL_FOREACH_DATA_RETVAL(j, data, length, r) {
r = parse_field(data, length, "PRIORITY=", &priority, &priority_len);
if (r < 0)
return r;
else if (r > 0)
continue;
r = parse_field(data, length, "_HOSTNAME=", &hostname, &hostname_len);
if (r < 0)
return r;
else if (r > 0)
continue;
r = parse_field(data, length, "SYSLOG_IDENTIFIER=", &identifier, &identifier_len);
if (r < 0)
return r;
else if (r > 0)
continue;
r = parse_field(data, length, "_COMM=", &comm, &comm_len);
if (r < 0)
return r;
else if (r > 0)
continue;
r = parse_field(data, length, "_PID=", &pid, &pid_len);
if (r < 0)
return r;
else if (r > 0)
continue;
r = parse_field(data, length, "SYSLOG_PID=", &fake_pid, &fake_pid_len);
if (r < 0)
return r;
else if (r > 0)
continue;
r = parse_field(data, length, "_SOURCE_REALTIME_TIMESTAMP=", &realtime, &realtime_len);
if (r < 0)
return r;
else if (r > 0)
continue;
r = parse_field(data, length, "_SOURCE_MONOTONIC_TIMESTAMP=", &monotonic, &monotonic_len);
if (r < 0)
return r;
else if (r > 0)
continue;
r = parse_field(data, length, "MESSAGE=", &message, &message_len);
r = parse_fieldv(data, length, fields, ELEMENTSOF(fields));
if (r < 0)
return r;
}
@ -500,7 +489,7 @@ static int output_verbose(
else {
_cleanup_free_ char *value = NULL;
r = parse_field(data, length, "_SOURCE_REALTIME_TIMESTAMP=", &value, NULL);
r = parse_field(data, length, "_SOURCE_REALTIME_TIMESTAMP=", strlen("_SOURCE_REALTIME_TIMESTAMP="), &value, NULL);
if (r < 0)
return r;
assert(r > 0);