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Cherry pick PR #3374: Optimistically read from /proc for process stat…
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…s. (#3607)

Refer to the original PR: #3374

b/341774149

Co-authored-by: aee <[email protected]>
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cobalt-github-releaser-bot and aee-google authored Jun 20, 2024
1 parent c155ebe commit ac2590b
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Showing 8 changed files with 508 additions and 10 deletions.
7 changes: 7 additions & 0 deletions base/BUILD.gn
Original file line number Diff line number Diff line change
Expand Up @@ -1065,6 +1065,13 @@ component("base") {
]
}

if (use_cobalt_customizations) {
sources += [
"process/internal_linux.cc",
"process/internal_linux.h",
]
}

if (!use_cobalt_customizations && (is_linux || is_chromeos || is_android)) {
sources += [
"files/file_path_watcher_inotify.cc",
Expand Down
31 changes: 21 additions & 10 deletions base/process/internal_linux.cc
Original file line number Diff line number Diff line change
Expand Up @@ -33,6 +33,7 @@ const char kProcDir[] = "/proc";

const char kStatFile[] = "stat";

#if !defined(STARBOARD)
FilePath GetProcPidDir(pid_t pid) {
return FilePath(kProcDir).Append(NumberToString(pid));
}
Expand All @@ -56,6 +57,7 @@ pid_t ProcDirSlotToPid(const char* d_name) {
}
return pid;
}
#endif // !defined(STARBOARD)

bool ReadProcFile(const FilePath& file, std::string* buffer) {
DCHECK(FilePath(kProcDir).IsParent(file));
Expand All @@ -70,10 +72,12 @@ bool ReadProcFile(const FilePath& file, std::string* buffer) {
return !buffer->empty();
}

#if !defined(STARBOARD)
bool ReadProcStats(pid_t pid, std::string* buffer) {
FilePath stat_file = internal::GetProcPidDir(pid).Append(kStatFile);
return ReadProcFile(stat_file, buffer);
}
#endif // !defined(STARBOARD)

bool ParseProcStats(const std::string& stats_data,
std::vector<std::string>* proc_stats) {
Expand All @@ -86,28 +90,29 @@ bool ParseProcStats(const std::string& stats_data,
// pid (process name) data1 data2 .... dataN
// Look for the closing paren by scanning backwards, to avoid being fooled by
// processes with ')' in the name.
size_t open_parens_idx = stats_data.find(" (");
size_t close_parens_idx = stats_data.rfind(") ");
if (open_parens_idx == std::string::npos ||
close_parens_idx == std::string::npos ||
open_parens_idx > close_parens_idx) {
size_t pid_end = stats_data.find(" (");
size_t comm_start = pid_end + 2;
size_t comm_end = stats_data.rfind(") ");
size_t state_start = comm_end + 2;
if (pid_end == std::string::npos ||
comm_end == std::string::npos ||
pid_end > comm_end) {
DLOG(WARNING) << "Failed to find matched parens in '" << stats_data << "'";
NOTREACHED();
return false;
}
open_parens_idx++;

proc_stats->clear();
// PID.
proc_stats->push_back(stats_data.substr(0, open_parens_idx));
proc_stats->push_back(stats_data.substr(0, pid_end));
// Process name without parentheses.
proc_stats->push_back(
stats_data.substr(open_parens_idx + 1,
close_parens_idx - (open_parens_idx + 1)));
stats_data.substr(comm_start,
comm_end - comm_start));

// Split the rest.
std::vector<std::string> other_stats = SplitString(
stats_data.substr(close_parens_idx + 2), " ",
stats_data.substr(state_start), " ",
base::TRIM_WHITESPACE, base::SPLIT_WANT_ALL);
for (const auto& i : other_stats)
proc_stats->push_back(i);
Expand Down Expand Up @@ -152,16 +157,19 @@ int64_t ReadStatFileAndGetFieldAsInt64(const FilePath& stat_file,
return GetProcStatsFieldAsInt64(proc_stats, field_num);
}

#if !defined(STARBOARD)
int64_t ReadProcStatsAndGetFieldAsInt64(pid_t pid, ProcStatsFields field_num) {
FilePath stat_file = internal::GetProcPidDir(pid).Append(kStatFile);
return ReadStatFileAndGetFieldAsInt64(stat_file, field_num);
}
#endif // !defined(STARBOARD)

int64_t ReadProcSelfStatsAndGetFieldAsInt64(ProcStatsFields field_num) {
FilePath stat_file = FilePath(kProcDir).Append("self").Append(kStatFile);
return ReadStatFileAndGetFieldAsInt64(stat_file, field_num);
}

#if !defined(STARBOARD)
size_t ReadProcStatsAndGetFieldAsSizeT(pid_t pid,
ProcStatsFields field_num) {
std::string stats_data;
Expand All @@ -172,6 +180,7 @@ size_t ReadProcStatsAndGetFieldAsSizeT(pid_t pid,
return 0;
return GetProcStatsFieldAsSizeT(proc_stats, field_num);
}
#endif // !defined(STARBOARD)

Time GetBootTime() {
FilePath path("/proc/stat");
Expand All @@ -189,6 +198,7 @@ Time GetBootTime() {
return Time::FromTimeT(btime);
}

#if !defined(STARBOARD)
TimeDelta GetUserCpuTimeSinceBoot() {
FilePath path("/proc/stat");
std::string contents;
Expand Down Expand Up @@ -228,6 +238,7 @@ TimeDelta ClockTicksToTimeDelta(int64_t clock_ticks) {

return Microseconds(Time::kMicrosecondsPerSecond * clock_ticks / kHertz);
}
#endif // !defined(STARBOARD)

} // namespace internal
} // namespace base
12 changes: 12 additions & 0 deletions base/process/internal_linux.h
Original file line number Diff line number Diff line change
Expand Up @@ -14,7 +14,9 @@
#include <string>
#include <vector>

#if !defined(STARBOARD)
#include "base/files/dir_reader_posix.h"
#endif // !defined(STARBOARD)
#include "base/files/file_path.h"
#include "base/process/process_handle.h"
#include "base/strings/string_number_conversions.h"
Expand All @@ -33,14 +35,17 @@ extern const char kProcDir[];
// "stat"
extern const char kStatFile[];

#if !defined(STARBOARD)
// Returns a FilePath to "/proc/pid".
base::FilePath GetProcPidDir(pid_t pid);
#endif // !defined(STARBOARD)

// Reads a file from /proc into a string. This is allowed on any thread as
// reading from /proc does not hit the disk. Returns true if the file can be
// read and is non-empty.
bool ReadProcFile(const FilePath& file, std::string* buffer);

#if !defined(STARBOARD)
// Take a /proc directory entry named |d_name|, and if it is the directory for
// a process, convert it to a pid_t.
// Returns 0 on failure.
Expand All @@ -50,6 +55,7 @@ pid_t ProcDirSlotToPid(const char* d_name);
// Reads /proc/<pid>/stat into |buffer|. Returns true if the file can be read
// and is non-empty.
bool ReadProcStats(pid_t pid, std::string* buffer);
#endif // !defined(STARBOARD)

// Takes |stats_data| and populates |proc_stats| with the values split by
// spaces. Taking into account the 2nd field may, in itself, contain spaces.
Expand Down Expand Up @@ -89,16 +95,21 @@ size_t GetProcStatsFieldAsSizeT(const std::vector<std::string>& proc_stats,
// ReadProcStats(). See GetProcStatsFieldAsInt64() for details.
int64_t ReadStatsFilendGetFieldAsInt64(const FilePath& stat_file,
ProcStatsFields field_num);
#if !defined(STARBOARD)
int64_t ReadProcStatsAndGetFieldAsInt64(pid_t pid, ProcStatsFields field_num);
#endif // !defined(STARBOARD)
int64_t ReadProcSelfStatsAndGetFieldAsInt64(ProcStatsFields field_num);

#if !defined(STARBOARD)
// Same as ReadProcStatsAndGetFieldAsInt64() but for size_t values.
size_t ReadProcStatsAndGetFieldAsSizeT(pid_t pid,
ProcStatsFields field_num);
#endif // !defined(STARBOARD)

// Returns the time that the OS started. Clock ticks are relative to this.
Time GetBootTime();

#if !defined(STARBOARD)
// Returns the amount of time spent in user space since boot across all CPUs.
TimeDelta GetUserCpuTimeSinceBoot();

Expand Down Expand Up @@ -130,6 +141,7 @@ void ForEachProcessTask(base::ProcessHandle process, Lambda&& lambda) {
lambda(tid, task_path);
}
}
#endif // !defined(STARBOARD)

} // namespace internal
} // namespace base
Expand Down
3 changes: 3 additions & 0 deletions cobalt/base/BUILD.gn
Original file line number Diff line number Diff line change
Expand Up @@ -67,6 +67,8 @@ static_library("base") {
"path_provider.h",
"polymorphic_downcast.h",
"polymorphic_equatable.h",
"process/process_metrics_helper.cc",
"process/process_metrics_helper.h",
"ref_counted_lock.h",
"source_location.cc",
"source_location.h",
Expand Down Expand Up @@ -117,6 +119,7 @@ target(gtest_target_type, "base_test") {
"c_val_time_interval_timer_stats_test.cc",
"circular_buffer_shell_unittest.cc",
"fixed_size_lru_cache_test.cc",
"process/process_metrics_helper_test.cc",
"statistics_test.cc",
"token_test.cc",
]
Expand Down
181 changes: 181 additions & 0 deletions cobalt/base/process/process_metrics_helper.cc
Original file line number Diff line number Diff line change
@@ -0,0 +1,181 @@
// Copyright 2024 The Cobalt Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include "cobalt/base/process/process_metrics_helper.h"

#include <atomic>
#include <cmath>
#include <memory>
#include <string>
#include <utility>
#include <vector>

#include "base/files/file_enumerator.h"
#include "base/files/file_path.h"
#include "base/files/file_util.h"
#include "base/memory/ptr_util.h"
#include "base/process/internal_linux.h"
#include "base/strings/string_number_conversions.h"
#include "base/strings/string_split.h"
#include "base/strings/string_util.h"
#include "base/time/time.h"

namespace base {

namespace {

static std::atomic<int> clock_ticks_per_s{0};

ProcessMetricsHelper::ReadCallback GetReadCallback(const FilePath& path) {
return BindOnce(
[](const FilePath& path) -> absl::optional<std::string> {
std::string contents;
if (!ReadFileToString(path, &contents)) return absl::nullopt;
return std::move(contents);
},
path);
}

double CalculateCPUUsageSeconds(const std::string& utime_string,
const std::string& stime_string,
int ticks_per_s) {
DCHECK_NE(ticks_per_s, 0);
double utime;
if (!StringToDouble(utime_string, &utime)) return 0.0;
double stime;
if (!StringToDouble(stime_string, &stime)) return 0.0;
return (utime + stime) / static_cast<double>(ticks_per_s);
}

} // namespace

// static
int ProcessMetricsHelper::GetClockTicksPerS() {
return clock_ticks_per_s.load();
}

// static
int ProcessMetricsHelper::GetClockTicksPerS(ReadCallback uptime_callback,
ReadCallback stat_callback) {
double current_uptime = 0.0;
{
auto uptime_contents = std::move(uptime_callback).Run();
if (!uptime_contents) return 0;
auto parts = SplitString(*uptime_contents, " ", TRIM_WHITESPACE,
SPLIT_WANT_NONEMPTY);
if (parts.size() == 0 || !StringToDouble(parts[0], &current_uptime) ||
current_uptime == 0.0) {
return 0;
}
}

auto fields = GetProcStatFields(std::move(stat_callback),
{internal::ProcStatsFields::VM_STARTTIME});
if (fields.size() != 1) return 0;
double process_starttime;
if (!StringToDouble(fields[0], &process_starttime) ||
process_starttime == 0.0)
return 0;
double ticks_per_s = process_starttime / current_uptime;
int rounded_up = 10 * static_cast<int>(std::ceil(ticks_per_s / 10.0));
return rounded_up;
}

// static
void ProcessMetricsHelper::PopulateClockTicksPerS() {
DCHECK_EQ(clock_ticks_per_s.load(), 0);
clock_ticks_per_s.store(
GetClockTicksPerS(GetReadCallback(FilePath("/proc/uptime")),
GetReadCallback(FilePath("/proc/self/stat"))));
}

// static
TimeDelta ProcessMetricsHelper::GetCumulativeCPUUsage() {
int ticks_per_s = clock_ticks_per_s.load();
if (ticks_per_s == 0) return TimeDelta();
return GetCPUUsage(FilePath("/proc/self"), ticks_per_s);
}

// static
Value ProcessMetricsHelper::GetCumulativeCPUUsagePerThread() {
int ticks_per_s = clock_ticks_per_s.load();
if (ticks_per_s == 0) return Value();
Value::List cpu_per_thread;
FileEnumerator file_enum(FilePath("/proc/self/task"), /*recursive=*/false,
FileEnumerator::DIRECTORIES);
for (FilePath path = file_enum.Next(); !path.empty();
path = file_enum.Next()) {
Fields fields =
GetProcStatFields(path, {0, internal::ProcStatsFields::VM_COMM,
internal::ProcStatsFields::VM_UTIME,
internal::ProcStatsFields::VM_STIME});
if (fields.size() != 4) continue;
int id;
if (!StringToInt(fields[0], &id)) continue;
Value::Dict entry =
Value::Dict()
.Set("id", id)
.Set("name", fields[1])
.Set("utime", fields[2])
.Set("stime", fields[3])
.Set("usage_seconds",
CalculateCPUUsageSeconds(fields[2], fields[3], ticks_per_s));
cpu_per_thread.Append(std::move(entry));
}
return Value(std::move(cpu_per_thread));
}

// static
ProcessMetricsHelper::Fields ProcessMetricsHelper::GetProcStatFields(
ReadCallback read_callback, std::initializer_list<int> indices) {
absl::optional<std::string> contents = std::move(read_callback).Run();
if (!contents) return Fields();

std::vector<std::string> proc_stats;
if (!internal::ParseProcStats(*contents, &proc_stats)) return Fields();

Fields fields;
for (int index : indices) {
if (index < 0 || index >= proc_stats.size()) return Fields();
fields.push_back(std::move(proc_stats[index]));
}
return std::move(fields);
}

// static
ProcessMetricsHelper::Fields ProcessMetricsHelper::GetProcStatFields(
const FilePath& path, std::initializer_list<int> indices) {
return ProcessMetricsHelper::GetProcStatFields(
GetReadCallback(path.Append("stat")), indices);
}

// static
TimeDelta ProcessMetricsHelper::GetCPUUsage(ReadCallback read_callback,
int ticks_per_s) {
auto fields = ProcessMetricsHelper::GetProcStatFields(
std::move(read_callback), {internal::ProcStatsFields::VM_UTIME,
internal::ProcStatsFields::VM_STIME});
if (fields.size() != 2) return TimeDelta();
return TimeDelta::FromSecondsD(
CalculateCPUUsageSeconds(fields[0], fields[1], ticks_per_s));
}

// static
TimeDelta ProcessMetricsHelper::GetCPUUsage(const FilePath& path,
int ticks_per_s) {
return ProcessMetricsHelper::GetCPUUsage(GetReadCallback(path.Append("stat")),
ticks_per_s);
}

} // namespace base
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