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#include "ProcfsMetricsProvider.h"
#if defined(OS_LINUX)
#include <Common/Exception.h>
#include <IO/ReadBufferFromMemory.h>
#include <IO/ReadHelpers.h>
#include <base/find_symbols.h>
#include <base/defines.h>
#include <Common/logger_useful.h>
#include <cassert>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <linux/taskstats.h>
namespace DB
{
namespace ErrorCodes
{
extern const int FILE_DOESNT_EXIST;
extern const int CANNOT_OPEN_FILE;
extern const int CANNOT_CLOSE_FILE;
extern const int CANNOT_READ_FROM_FILE_DESCRIPTOR;
}
static constexpr auto thread_schedstat = "/proc/thread-self/schedstat";
static constexpr auto thread_stat = "/proc/thread-self/stat";
static constexpr auto thread_io = "/proc/thread-self/io";
namespace
{
[[noreturn]] inline void throwWithFailedToOpenFile(const std::string & filename)
{
throwFromErrno(
"Cannot open file " + filename,
errno == ENOENT ? ErrorCodes::FILE_DOESNT_EXIST : ErrorCodes::CANNOT_OPEN_FILE);
}
inline void emitErrorMsgWithFailedToCloseFile(const std::string & filename)
{
try
{
throwFromErrno(
"File descriptor for \"" + filename + "\" could not be closed. "
"Something seems to have gone wrong. Inspect errno.", ErrorCodes::CANNOT_CLOSE_FILE);
}
catch (const ErrnoException &)
{
DB::tryLogCurrentException(__PRETTY_FUNCTION__);
}
}
ssize_t readFromFD(const int fd, const char * filename, char * buf, size_t buf_size)
{
ssize_t res = 0;
do
{
res = ::pread(fd, buf, buf_size, 0);
if (-1 == res)
{
if (errno == EINTR)
continue;
throwFromErrno(
"Cannot read from file " + std::string(filename),
ErrorCodes::CANNOT_READ_FROM_FILE_DESCRIPTOR);
}
assert(res >= 0);
break;
} while (true);
return res;
}
}
bool ProcfsMetricsProvider::isAvailable() noexcept
{
struct stat sb;
int res = ::stat(thread_schedstat, &sb);
/// Verify that procfs is mounted, one of the stats file exists and is a regular file
return res != -1 && (sb.st_mode & S_IFMT) == S_IFREG;
}
ProcfsMetricsProvider::ProcfsMetricsProvider(pid_t /*tid*/)
{
thread_schedstat_fd = ::open(thread_schedstat, O_RDONLY | O_CLOEXEC);
if (-1 == thread_schedstat_fd)
{
throwWithFailedToOpenFile(thread_schedstat);
}
thread_stat_fd = ::open(thread_stat, O_RDONLY | O_CLOEXEC);
if (-1 == thread_stat_fd)
{
int err = ::close(thread_schedstat_fd);
chassert(!err || errno == EINTR);
throwWithFailedToOpenFile(thread_stat);
}
thread_io_fd = ::open(thread_io, O_RDONLY | O_CLOEXEC);
if (-1 != thread_io_fd)
{
stats_version = 3;
}
}
ProcfsMetricsProvider::~ProcfsMetricsProvider()
{
if (stats_version >= 3 && 0 != ::close(thread_io_fd))
emitErrorMsgWithFailedToCloseFile(thread_io);
if (0 != ::close(thread_stat_fd))
emitErrorMsgWithFailedToCloseFile(thread_stat);
if (0 != ::close(thread_schedstat_fd))
emitErrorMsgWithFailedToCloseFile(thread_schedstat);
}
void ProcfsMetricsProvider::getTaskStats(::taskstats & out_stats) const
{
constexpr size_t buf_size = 1024;
char buf[buf_size];
out_stats.version = stats_version;
readParseAndSetThreadCPUStat(out_stats, buf, buf_size);
readParseAndSetThreadBlkIOStat(out_stats, buf, buf_size);
if (stats_version >= 3)
{
readParseAndSetThreadIOStat(out_stats, buf, buf_size);
}
}
void ProcfsMetricsProvider::readParseAndSetThreadCPUStat(::taskstats & out_stats, char * buf, size_t buf_size) const
{
ssize_t res = readFromFD(thread_schedstat_fd, thread_schedstat, buf, buf_size);
ReadBufferFromMemory in_schedstat(buf, res);
readIntText(out_stats.cpu_run_virtual_total, in_schedstat);
skipWhitespaceIfAny(in_schedstat);
readIntText(out_stats.cpu_delay_total, in_schedstat);
}
void ProcfsMetricsProvider::readParseAndSetThreadBlkIOStat(::taskstats & out_stats, char * buf, size_t buf_size) const
{
ssize_t res = readFromFD(thread_stat_fd, thread_stat, buf, buf_size - 1);
ReadBufferFromMemory in_stat(buf, res);
/// We need to skip the first 41 fields of the string read from /proc/thread-self/stat.
for (int i = 0; i < 41; ++i)
{
in_stat.position() = find_first_symbols<' ', '\t'>(in_stat.position(), in_stat.buffer().end());
skipWhitespaceIfAny(in_stat);
}
/// Read field #42 - Aggregated block I/O delays, measured in clock ticks (centiseconds)
readIntText(out_stats.blkio_delay_total, in_stat);
out_stats.blkio_delay_total *= 10000000ul; /// We need to return time in nanoseconds
}
void ProcfsMetricsProvider::readParseAndSetThreadIOStat(::taskstats & out_stats, char * buf, size_t buf_size) const
{
ssize_t res = readFromFD(thread_io_fd, thread_io, buf, buf_size);
ReadBufferFromMemory in_thread_io(buf, res);
assertString("rchar:", in_thread_io);
skipWhitespaceIfAny(in_thread_io);
readIntText(out_stats.read_char, in_thread_io);
skipWhitespaceIfAny(in_thread_io);
assertString("wchar:", in_thread_io);
skipWhitespaceIfAny(in_thread_io);
readIntText(out_stats.write_char, in_thread_io);
skipWhitespaceIfAny(in_thread_io);
skipToNextLineOrEOF(in_thread_io);
skipToNextLineOrEOF(in_thread_io);
assertString("read_bytes:", in_thread_io);
skipWhitespaceIfAny(in_thread_io);
readIntText(out_stats.read_bytes, in_thread_io);
skipWhitespaceIfAny(in_thread_io);
assertString("write_bytes:", in_thread_io);
skipWhitespaceIfAny(in_thread_io);
readIntText(out_stats.write_bytes, in_thread_io);
}
}
#endif
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