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Break diags log rotation into subroutines #13254

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a25823b
Break diag log rotation into subroutines
Jun 10, 2026
fd01a92
Address Copilot review
JosiahWI Jun 10, 2026
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9 changes: 9 additions & 0 deletions include/tscore/DiagsTypes.h
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Original file line number Diff line number Diff line change
Expand Up @@ -274,4 +274,13 @@ class Diags : public DebugInterface
{
ink_mutex_release(&tag_table_lock);
}

bool roll_diags_on_filesize(int mb_threshold);
bool roll_diags_on_interval(int interval);

bool roll_streams_on_filesize(int mb_threshold);
bool roll_streams_on_interval(int interval);

std::unique_ptr<BaseLogFile> remake_logfile(BaseLogFile const *logfile);
void swap_diagslog(BaseLogFile *new_diags);
};
295 changes: 174 additions & 121 deletions src/tscore/Diags.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -48,6 +48,9 @@
#include "tscore/Regression.h"
#include "tscore/Diags.h"
#include "ts/ts.h"

#include <memory>
#include <stdexcept>
#include <string_view>

int DiagsConfigState::_enabled[2] = {0, 0};
Expand Down Expand Up @@ -503,17 +506,10 @@ Diags::reseat_diagslog()
return false;
}
fflush(diags_log->m_fp);
char *oldname = ats_strdup(diags_log->get_name());
log_log_trace("in %s for diags.log, oldname=%s\n", __func__, oldname);
BaseLogFile *n = new BaseLogFile(oldname);
if (setup_diagslog(n)) {
BaseLogFile *old_diags = diags_log;
lock();
diags_log = n;
unlock();
delete old_diags;

if (std::unique_ptr<BaseLogFile> new_logfile{remake_logfile(diags_log)}; new_logfile) {
swap_diagslog(new_logfile.release());
}
ats_free(oldname);
return true;
}

Expand Down Expand Up @@ -546,53 +542,16 @@ Diags::should_roll_diagslog()
if (diags_log && diags_log->is_init()) {
if (diagslog_rolling_enabled == RollingEnabledValues::ROLL_ON_SIZE ||
diagslog_rolling_enabled == RollingEnabledValues::ROLL_ON_TIME_OR_SIZE) {
// if we can't even check the file, we can forget about rotating
struct stat buf;
if (fstat(fileno(diags_log->m_fp), &buf) != 0) {
try {
ret_val = roll_diags_on_filesize(diagslog_rolling_size);
} catch (std::runtime_error const &) {
return false;
}

off_t size = buf.st_size;
if (diagslog_rolling_size != -1 && size >= (static_cast<off_t>(diagslog_rolling_size) * BYTES_IN_MB)) {
fflush(diags_log->m_fp);
if (diags_log->roll()) {
char *oldname = ats_strdup(diags_log->get_name());
log_log_trace("in %s for diags.log, oldname=%s\n", __func__, oldname);
BaseLogFile *n = new BaseLogFile(oldname);
if (setup_diagslog(n)) {
BaseLogFile *old_diags = diags_log;
lock();
diags_log = n;
unlock();
delete old_diags;
}
ats_free(oldname);
ret_val = true;
}
}
}

if (diagslog_rolling_enabled == RollingEnabledValues::ROLL_ON_TIME ||
diagslog_rolling_enabled == RollingEnabledValues::ROLL_ON_TIME_OR_SIZE) {
time_t now = time(nullptr);
if (diagslog_rolling_interval != -1 && (now - diagslog_time_last_roll) >= diagslog_rolling_interval) {
fflush(diags_log->m_fp);
if (diags_log->roll()) {
diagslog_time_last_roll = now;
char *oldname = ats_strdup(diags_log->get_name());
log_log_trace("in %s for diags.log, oldname=%s\n", __func__, oldname);
BaseLogFile *n = new BaseLogFile(oldname);
if (setup_diagslog(n)) {
BaseLogFile *old_diags = diags_log;
lock();
diags_log = n;
unlock();
delete old_diags;
}
ats_free(oldname);
ret_val = true;
}
}
ret_val = roll_diags_on_interval(diagslog_rolling_interval);
}
}

Expand All @@ -619,8 +578,7 @@ Diags::should_roll_outputlog()
ink_assert(stdout_log != nullptr);
ink_assert(stderr_log != nullptr);

bool ret_val = false;
bool need_consider_stderr = true;
bool ret_val = false;

log_log_trace("%s was called\n", __func__);
log_log_trace("%s: rolling_enabled = %d, output_rolling_size = %d, output_rolling_interval = %d\n", __func__,
Expand All @@ -634,83 +592,19 @@ Diags::should_roll_outputlog()
if (stdout_log->is_init()) {
if (outputlog_rolling_enabled == RollingEnabledValues::ROLL_ON_SIZE ||
outputlog_rolling_enabled == RollingEnabledValues::ROLL_ON_TIME_OR_SIZE) {
// if we can't even check the file, we can forget about rotating
struct stat buf;
if (fstat(fileno(stdout_log->m_fp), &buf) != 0) {
try {
ret_val = roll_streams_on_filesize(outputlog_rolling_size);
} catch (std::runtime_error const &) {
return false;
}

off_t size = buf.st_size;
if (outputlog_rolling_size != -1 && size >= static_cast<off_t>(outputlog_rolling_size) * BYTES_IN_MB) {
// since usually stdout and stderr are the same file on disk, we should just
// play it safe and just flush both BaseLogFiles
if (stderr_log->is_init()) {
fflush(stderr_log->m_fp);
}
fflush(stdout_log->m_fp);

if (stdout_log->roll()) {
char *oldname = ats_strdup(stdout_log->get_name());
log_log_trace("in %s(), oldname=%s\n", __func__, oldname);
set_std_output(StdStream::STDOUT, oldname);

// if stderr and stdout are redirected to the same place, we should
// update the stderr_log object as well
if (!strcmp(oldname, stderr_log->get_name())) {
log_log_trace("oldname == stderr_log->get_name()\n");
set_std_output(StdStream::STDERR, oldname);
need_consider_stderr = false;
}
ats_free(oldname);
ret_val = true;
}
}
}

if (outputlog_rolling_enabled == RollingEnabledValues::ROLL_ON_TIME ||
outputlog_rolling_enabled == RollingEnabledValues::ROLL_ON_TIME_OR_SIZE) {
time_t now = time(nullptr);
if (outputlog_rolling_interval != -1 && (now - outputlog_time_last_roll) >= outputlog_rolling_interval) {
// since usually stdout and stderr are the same file on disk, we should just
// play it safe and just flush both BaseLogFiles
if (stderr_log->is_init()) {
fflush(stderr_log->m_fp);
}
fflush(stdout_log->m_fp);

if (stdout_log->roll()) {
outputlog_time_last_roll = now;
char *oldname = ats_strdup(stdout_log->get_name());
log_log_trace("in %s, oldname=%s\n", __func__, oldname);
set_std_output(StdStream::STDOUT, oldname);

// if stderr and stdout are redirected to the same place, we should
// update the stderr_log object as well
if (!strcmp(oldname, stderr_log->get_name())) {
log_log_trace("oldname == stderr_log->get_name()\n");
set_std_output(StdStream::STDERR, oldname);
need_consider_stderr = false;
}
ats_free(oldname);
ret_val = true;
}
}
ret_val = roll_streams_on_interval(outputlog_rolling_interval);
}
}

// This assertion has to be true since log rolling for traffic.out is only ever enabled
// (and useful) when traffic_server is NOT running in stand alone mode. If traffic_server
// is NOT running in stand alone mode, then stderr and stdout SHOULD ALWAYS be pointing
// to the same file (traffic.out).
//
// If for some reason, someone wants the feature to have stdout pointing to some file on
// disk, and stderr pointing to a different file on disk, and then also wants both files to
// rotate according to the (same || different) scheme, it would not be difficult to add
// some more config options in records.yaml and said feature into this function.
if (ret_val) {
ink_assert(!need_consider_stderr);

@JosiahWI JosiahWI Jun 10, 2026

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Instead of asserting that this flag was set, I am asserting at an earlier point that the condition for setting the flag is met. The code was originally designed to be a little easier to change if more output stream flexibility was needed. Since that obviously hasn't happened for a long time, and was only a small amount of code, I have removed the extra logic flow and this flag entirely, simplifying the code.

}

return ret_val;
}

Expand Down Expand Up @@ -810,3 +704,162 @@ Diags::rebind_std_stream(StdStream stream, int new_fd)
}
return false;
}

bool
Diags::roll_diags_on_filesize(int mb_threshold)
{
// if we can't even check the file, we can forget about rotating
struct stat buf;
if (fstat(fileno(diags_log->m_fp), &buf) != 0) {
throw std::runtime_error{"could not stat diags log"};
}

off_t size = buf.st_size;
if (mb_threshold == -1 || size < static_cast<off_t>(mb_threshold) * BYTES_IN_MB) {
return false;
}

fflush(diags_log->m_fp);

if (!diags_log->roll()) {
return false;
}

if (std::unique_ptr<BaseLogFile> new_logfile{remake_logfile(diags_log)}; new_logfile) {
swap_diagslog(new_logfile.release());
}
return true;
}

bool
Diags::roll_diags_on_interval(int interval)
{
time_t now = time(nullptr);
if (interval == -1 || (now - diagslog_time_last_roll) < interval) {
return false;
}

fflush(diags_log->m_fp);

if (!diags_log->roll()) {
return false;
}

diagslog_time_last_roll = now;
if (std::unique_ptr<BaseLogFile> new_logfile{remake_logfile(diags_log)}; new_logfile) {
swap_diagslog(new_logfile.release());
}
return true;
}

bool
Diags::roll_streams_on_filesize(int mb_threshold)
{
// if we can't even check the file, we can forget about rotating
struct stat buf;
if (fstat(fileno(stdout_log->m_fp), &buf) != 0) {
throw std::runtime_error{"could not stat output log"};
}

off_t size = buf.st_size;
if (mb_threshold == -1 || size < static_cast<off_t>(mb_threshold) * BYTES_IN_MB) {
return false;
}

// since usually stdout and stderr are the same file on disk, we should just
// play it safe and just flush both BaseLogFiles
if (stderr_log->is_init()) {
fflush(stderr_log->m_fp);
}
fflush(stdout_log->m_fp);

if (!stdout_log->roll()) {
return false;
}

char *oldname = ats_strdup(stdout_log->get_name());
log_log_trace("in %s(), oldname=%s\n", __func__, oldname);
set_std_output(StdStream::STDOUT, oldname);

// This assertion has to be true since log rolling for traffic.out is only ever enabled
// (and useful) when traffic_server is NOT running in stand alone mode. If traffic_server
// is NOT running in stand alone mode, then stderr and stdout SHOULD ALWAYS be pointing
// to the same file (traffic.out).
//
// If for some reason, someone wants the feature to have stdout pointing to some file on
// disk, and stderr pointing to a different file on disk, and then also wants both files to
// rotate according to the (same || different) scheme, it would not be difficult to add
// some more config options in records.yaml and said feature into this function.
ink_release_assert(0 == strcmp(stdout_log->get_name(), stderr_log->get_name()));
log_log_trace("oldname == stderr_log->get_name()\n");
set_std_output(StdStream::STDERR, oldname);

ats_free(oldname);
return true;
}

bool
Diags::roll_streams_on_interval(int interval)
{
time_t now = time(nullptr);
if (interval == -1 || (now - outputlog_time_last_roll) < interval) {
return false;
}

// since usually stdout and stderr are the same file on disk, we should just
// play it safe and just flush both BaseLogFiles
if (stderr_log->is_init()) {
fflush(stderr_log->m_fp);
}
fflush(stdout_log->m_fp);

if (!stdout_log->roll()) {
return false;
}

outputlog_time_last_roll = now;
char *oldname = ats_strdup(stdout_log->get_name());
log_log_trace("in %s, oldname=%s\n", __func__, oldname);
set_std_output(StdStream::STDOUT, oldname);

// This assertion has to be true since log rolling for traffic.out is only ever enabled
// (and useful) when traffic_server is NOT running in stand alone mode. If traffic_server
// is NOT running in stand alone mode, then stderr and stdout SHOULD ALWAYS be pointing
// to the same file (traffic.out).
//
// If for some reason, someone wants the feature to have stdout pointing to some file on
// disk, and stderr pointing to a different file on disk, and then also wants both files to
// rotate according to the (same || different) scheme, it would not be difficult to add
// some more config options in records.yaml and said feature into this function.
ink_release_assert(0 == strcmp(stdout_log->get_name(), stderr_log->get_name()));
log_log_trace("oldname == stderr_log->get_name()\n");
set_std_output(StdStream::STDERR, oldname);

ats_free(oldname);
return true;
}

std::unique_ptr<BaseLogFile>
Diags::remake_logfile(BaseLogFile const *logfile)
{
char *oldname = ats_strdup(logfile->get_name());
log_log_trace("in %s for diags.log, oldname=%s\n", __func__, oldname);
auto new_logfile = std::make_unique<BaseLogFile>(oldname);
ats_free(oldname);

if (!setup_diagslog(new_logfile.get())) {
return nullptr;
}

return new_logfile;
}

void
Diags::swap_diagslog(BaseLogFile *new_diags)
{
BaseLogFile *old_diags = diags_log;
lock();
diags_log = new_diags;
unlock();
delete old_diags;
}