Move init bootcharting onto its own thread.

This reduces the overhead when bootcharting is on (obviously), but also
removes the "do we need to do anything for bootcharting?" check in cases
where we're not bootcharting.

Bug: http://b/23478578
Bug: http://b/33450491
Test: rebooted with bootcharting on/off
Change-Id: Id8746b5023b17d7615679eba0bcd02aee048ef1a

3 files changed, 126 insertions, 156 deletions

diff --git a/init/bootchart.cpp b/init/bootchart.cpp
index 7a8a3d53f..4a9c32e2c 100644
--- a/init/bootchart.cpp
+++ b/init/bootchart.cpp
@@ -15,7 +15,7 @@
  */
 
 #include "bootchart.h"
-#include "log.h"
+
 #include "property_service.h"
 
 #include <dirent.h>
@@ -29,197 +29,170 @@
 #include <time.h>
 #include <unistd.h>
 
+#include <chrono>
+#include <condition_variable>
 #include <memory>
+#include <mutex>
 #include <string>
+#include <thread>
 #include <vector>
 
 #include <android-base/file.h>
+#include <android-base/logging.h>
 #include <android-base/stringprintf.h>
 
 using android::base::StringPrintf;
+using namespace std::chrono_literals;
 
-static constexpr const char* LOG_STAT = "/data/bootchart/proc_stat.log";
-static constexpr const char* LOG_PROC = "/data/bootchart/proc_ps.log";
-static constexpr const char* LOG_DISK = "/data/bootchart/proc_diskstats.log";
-static constexpr const char* LOG_HEADER = "/data/bootchart/header";
-
-// Polling period in ms.
-static constexpr int BOOTCHART_POLLING_MS = 200;
-
-static long long g_last_bootchart_time;
+static std::thread* g_bootcharting_thread;
 
-static bool g_bootcharting = false;
-
-static FILE* g_stat_log;
-static FILE* g_proc_log;
-static FILE* g_disk_log;
+static std::mutex g_bootcharting_finished_mutex;
+static std::condition_variable g_bootcharting_finished_cv;
+static bool g_bootcharting_finished;
 
 static long long get_uptime_jiffies() {
-    std::string uptime;
-    if (!android::base::ReadFileToString("/proc/uptime", &uptime)) {
-        return 0;
-    }
-    return 100LL * strtod(uptime.c_str(), NULL);
+  std::string uptime;
+  if (!android::base::ReadFileToString("/proc/uptime", &uptime)) return 0;
+  return 100LL * strtod(uptime.c_str(), NULL);
 }
 
-static void log_header() {
-    char date[32];
-    time_t now_t = time(NULL);
-    struct tm now = *localtime(&now_t);
-    strftime(date, sizeof(date), "%F %T", &now);
-
-    utsname uts;
-    if (uname(&uts) == -1) {
-        return;
-    }
-
-    std::string fingerprint = property_get("ro.build.fingerprint");
-    if (fingerprint.empty()) {
-        return;
-    }
-
-    std::string kernel_cmdline;
-    android::base::ReadFileToString("/proc/cmdline", &kernel_cmdline);
+static std::unique_ptr<FILE, decltype(&fclose)> fopen_unique(const char* filename,
+                                                             const char* mode) {
+  std::unique_ptr<FILE, decltype(&fclose)> result(fopen(filename, mode), fclose);
+  if (!result) PLOG(ERROR) << "bootchart: failed to open " << filename;
+  return result;
+}
 
-    FILE* out = fopen(LOG_HEADER, "we");
-    if (out == NULL) {
-        return;
-    }
-    fprintf(out, "version = Android init 0.8\n");
-    fprintf(out, "title = Boot chart for Android (%s)\n", date);
-    fprintf(out, "system.uname = %s %s %s %s\n", uts.sysname, uts.release, uts.version, uts.machine);
-    fprintf(out, "system.release = %s\n", fingerprint.c_str());
-    // TODO: use /proc/cpuinfo "model name" line for x86, "Processor" line for arm.
-    fprintf(out, "system.cpu = %s\n", uts.machine);
-    fprintf(out, "system.kernel.options = %s\n", kernel_cmdline.c_str());
-    fclose(out);
+static void log_header() {
+  char date[32];
+  time_t now_t = time(NULL);
+  struct tm now = *localtime(&now_t);
+  strftime(date, sizeof(date), "%F %T", &now);
+
+  utsname uts;
+  if (uname(&uts) == -1) return;
+
+  std::string fingerprint = property_get("ro.build.fingerprint");
+  if (fingerprint.empty()) return;
+
+  std::string kernel_cmdline;
+  android::base::ReadFileToString("/proc/cmdline", &kernel_cmdline);
+
+  auto fp = fopen_unique("/data/bootchart/header", "we");
+  if (!fp) return;
+  fprintf(&*fp, "version = Android init 0.8\n");
+  fprintf(&*fp, "title = Boot chart for Android (%s)\n", date);
+  fprintf(&*fp, "system.uname = %s %s %s %s\n", uts.sysname, uts.release, uts.version, uts.machine);
+  fprintf(&*fp, "system.release = %s\n", fingerprint.c_str());
+  // TODO: use /proc/cpuinfo "model name" line for x86, "Processor" line for arm.
+  fprintf(&*fp, "system.cpu = %s\n", uts.machine);
+  fprintf(&*fp, "system.kernel.options = %s\n", kernel_cmdline.c_str());
 }
 
 static void log_uptime(FILE* log) {
-    fprintf(log, "%lld\n", get_uptime_jiffies());
+  fprintf(log, "%lld\n", get_uptime_jiffies());
 }
 
 static void log_file(FILE* log, const char* procfile) {
-    log_uptime(log);
+  log_uptime(log);
 
-    std::string content;
-    if (android::base::ReadFileToString(procfile, &content)) {
-        fprintf(log, "%s\n", content.c_str());
-    }
+  std::string content;
+  if (android::base::ReadFileToString(procfile, &content)) {
+    fprintf(log, "%s\n", content.c_str());
+  }
 }
 
-static void log_processes() {
-    log_uptime(g_proc_log);
-
-    std::unique_ptr<DIR, int(*)(DIR*)> dir(opendir("/proc"), closedir);
-    struct dirent* entry;
-    while ((entry = readdir(dir.get())) != NULL) {
-        // Only match numeric values.
-        int pid = atoi(entry->d_name);
-        if (pid == 0) continue;
-
-        // /proc/<pid>/stat only has truncated task names, so get the full
-        // name from /proc/<pid>/cmdline.
-        std::string cmdline;
-        android::base::ReadFileToString(StringPrintf("/proc/%d/cmdline", pid), &cmdline);
-        const char* full_name = cmdline.c_str(); // So we stop at the first NUL.
-
-        // Read process stat line.
-        std::string stat;
-        if (android::base::ReadFileToString(StringPrintf("/proc/%d/stat", pid), &stat)) {
-            if (!cmdline.empty()) {
-                // Substitute the process name with its real name.
-                size_t open = stat.find('(');
-                size_t close = stat.find_last_of(')');
-                if (open != std::string::npos && close != std::string::npos) {
-                    stat.replace(open + 1, close - open - 1, full_name);
-                }
-            }
-            fputs(stat.c_str(), g_proc_log);
+static void log_processes(FILE* log) {
+  log_uptime(log);
+
+  std::unique_ptr<DIR, int(*)(DIR*)> dir(opendir("/proc"), closedir);
+  struct dirent* entry;
+  while ((entry = readdir(dir.get())) != NULL) {
+    // Only match numeric values.
+    int pid = atoi(entry->d_name);
+    if (pid == 0) continue;
+
+    // /proc/<pid>/stat only has truncated task names, so get the full
+    // name from /proc/<pid>/cmdline.
+    std::string cmdline;
+    android::base::ReadFileToString(StringPrintf("/proc/%d/cmdline", pid), &cmdline);
+    const char* full_name = cmdline.c_str(); // So we stop at the first NUL.
+
+    // Read process stat line.
+    std::string stat;
+    if (android::base::ReadFileToString(StringPrintf("/proc/%d/stat", pid), &stat)) {
+      if (!cmdline.empty()) {
+        // Substitute the process name with its real name.
+        size_t open = stat.find('(');
+        size_t close = stat.find_last_of(')');
+        if (open != std::string::npos && close != std::string::npos) {
+          stat.replace(open + 1, close - open - 1, full_name);
         }
+      }
+      fputs(stat.c_str(), log);
     }
+  }
 
-    fputc('\n', g_proc_log);
+  fputc('\n', log);
 }
 
-static int do_bootchart_start() {
-    // We don't care about the content, but we do care that /data/bootchart/enabled actually exists.
-    std::string start;
-    if (!android::base::ReadFileToString("/data/bootchart/enabled", &start)) {
-        LOG(VERBOSE) << "Not bootcharting";
-        return 0;
-    }
+static void bootchart_thread_main() {
+  LOG(INFO) << "Bootcharting started";
 
-    // Open log files.
-    std::unique_ptr<FILE, decltype(&fclose)> stat_log(fopen(LOG_STAT, "we"), fclose);
-    if (!stat_log) {
-        PLOG(ERROR) << "Bootcharting couldn't open " << LOG_STAT;
-        return -1;
-    }
-    std::unique_ptr<FILE, decltype(&fclose)> proc_log(fopen(LOG_PROC, "we"), fclose);
-    if (!proc_log) {
-        PLOG(ERROR) << "Bootcharting couldn't open " << LOG_PROC;
-        return -1;
-    }
-    std::unique_ptr<FILE, decltype(&fclose)> disk_log(fopen(LOG_DISK, "we"), fclose);
-    if (!disk_log) {
-        PLOG(ERROR) << "Bootcharting couldn't open " << LOG_DISK;
-        return -1;
+  // Open log files.
+  auto stat_log = fopen_unique("/data/bootchart/proc_stat.log", "we");
+  if (!stat_log) return;
+  auto proc_log = fopen_unique("/data/bootchart/proc_ps.log", "we");
+  if (!proc_log) return;
+  auto disk_log = fopen_unique("/data/bootchart/proc_diskstats.log", "we");
+  if (!disk_log) return;
+
+  log_header();
+
+  while (true) {
+    {
+      std::unique_lock<std::mutex> lock(g_bootcharting_finished_mutex);
+      g_bootcharting_finished_cv.wait_for(lock, 200ms);
+      if (g_bootcharting_finished) break;
     }
 
-    LOG(INFO) << "Bootcharting started";
-    g_stat_log = stat_log.release();
-    g_proc_log = proc_log.release();
-    g_disk_log = disk_log.release();
-    g_bootcharting = true;
-    log_header();
+    log_file(&*stat_log, "/proc/stat");
+    log_file(&*disk_log, "/proc/diskstats");
+    log_processes(&*proc_log);
+  }
 
-    return 0;
+  LOG(INFO) << "Bootcharting finished";
 }
 
-static void do_bootchart_step() {
-    log_file(g_stat_log, "/proc/stat");
-    log_file(g_disk_log, "/proc/diskstats");
-    log_processes();
+static int do_bootchart_start() {
+  // We don't care about the content, but we do care that /data/bootchart/enabled actually exists.
+  std::string start;
+  if (!android::base::ReadFileToString("/data/bootchart/enabled", &start)) {
+    LOG(VERBOSE) << "Not bootcharting";
+    return 0;
+  }
+
+  g_bootcharting_thread = new std::thread(bootchart_thread_main);
+  return 0;
 }
 
 static int do_bootchart_stop() {
-    if (!g_bootcharting) return 0;
-
-    LOG(INFO) << "Bootcharting finished";
-    g_bootcharting = false;
-    fclose(g_stat_log);
-    fclose(g_disk_log);
-    fclose(g_proc_log);
-    return 0;
+  if (!g_bootcharting_thread) return 0;
+
+  // Tell the worker thread it's time to quit.
+  {
+    std::lock_guard<std::mutex> lock(g_bootcharting_finished_mutex);
+    g_bootcharting_finished = true;
+    g_bootcharting_finished_cv.notify_one();
+  }
+
+  g_bootcharting_thread->join();
+  delete g_bootcharting_thread;
+  g_bootcharting_thread = nullptr;
+  return 0;
 }
 
 int do_bootchart(const std::vector<std::string>& args) {
-    if (args[1] == "start") return do_bootchart_start();
-    return do_bootchart_stop();
-}
-
-void bootchart_sample(int* timeout) {
-    // Do we have any more bootcharting to do?
-    if (!g_bootcharting) return;
-
-    long long current_time = 10LL * get_uptime_jiffies();
-    int elapsed_time = current_time - g_last_bootchart_time;
-
-    if (elapsed_time >= BOOTCHART_POLLING_MS) {
-        while (elapsed_time >= BOOTCHART_POLLING_MS) {
-            elapsed_time -= BOOTCHART_POLLING_MS;
-        }
-
-        g_last_bootchart_time = current_time;
-        do_bootchart_step();
-    }
-
-    // Schedule another?
-    if (g_bootcharting) {
-        int remaining_time = BOOTCHART_POLLING_MS - elapsed_time;
-        if (*timeout < 0 || *timeout > remaining_time) {
-            *timeout = remaining_time;
-        }
-    }
+  if (args[1] == "start") return do_bootchart_start();
+  return do_bootchart_stop();
 }
diff --git a/init/bootchart.h b/init/bootchart.h
index 1e8d0f865..0e3593d8c 100644
--- a/init/bootchart.h
+++ b/init/bootchart.h
@@ -21,6 +21,5 @@
 #include <vector>
 
 int do_bootchart(const std::vector<std::string>& args);
-void bootchart_sample(int* timeout);
 
 #endif /* _BOOTCHART_H */
diff --git a/init/init.cpp b/init/init.cpp
index 2d474c730..60eac4818 100644
--- a/init/init.cpp
+++ b/init/init.cpp
@@ -850,8 +850,6 @@ int main(int argc, char** argv) {
         // If there's more work to do, wake up again immediately.
         if (am.HasMoreCommands()) epoll_timeout_ms = 0;
 
-        bootchart_sample(&epoll_timeout_ms);
-
         epoll_event ev;
         int nr = TEMP_FAILURE_RETRY(epoll_wait(epoll_fd, &ev, 1, epoll_timeout_ms));
         if (nr == -1) {