init start time tracking.

With this change, init sets a property "init.start" to show the
CLOCK_BOOTTIME time at which init itself started, and for each service
an "init.svc.<name>.start" property to show the CLOCK_BOOTTIME time at
which that service was most recently started.

These times can be used by tools like bootstat to track boot time.

As part of this change, move init over to std::chrono. Also, rather than
make the command-line argument handling more complex, I've switched to
using an environment variable for communication between first- and
second-stage init, and added another environment variable to pass the
start time of the first stage through to the second stage.

Bug: http://b/32780225
Test: manual
Change-Id: Ia65a623e1866ea688b9a5433d6507926ce301dfe
diff --git a/init/service.cpp b/init/service.cpp
index 9fa11b8..a2099b0 100644
--- a/init/service.cpp
+++ b/init/service.cpp
@@ -17,6 +17,7 @@
 #include "service.h"
 
 #include <fcntl.h>
+#include <inttypes.h>
 #include <linux/securebits.h>
 #include <sched.h>
 #include <sys/mount.h>
@@ -51,9 +52,6 @@
 using android::base::StringPrintf;
 using android::base::WriteStringToFile;
 
-#define CRITICAL_CRASH_THRESHOLD    4       // if we crash >4 times ...
-#define CRITICAL_CRASH_WINDOW       (4*60)  // ... in 4 minutes, goto recovery
-
 static std::string ComputeContextFromExecutable(std::string& service_name,
                                                 const std::string& service_path) {
     std::string computed_context;
@@ -154,8 +152,8 @@
 
 Service::Service(const std::string& name, const std::string& classname,
                  const std::vector<std::string>& args)
-    : name_(name), classname_(classname), flags_(0), pid_(0), time_started_(0),
-      time_crashed_(0), nr_crashed_(0), uid_(0), gid_(0), namespace_flags_(0),
+    : name_(name), classname_(classname), flags_(0), pid_(0),
+      crash_count_(0), uid_(0), gid_(0), namespace_flags_(0),
       seclabel_(""), ioprio_class_(IoSchedClass_NONE), ioprio_pri_(0),
       priority_(0), oom_score_adjust_(-1000), args_(args) {
     onrestart_.InitSingleTrigger("onrestart");
@@ -168,7 +166,7 @@
                  const std::string& seclabel,
                  const std::vector<std::string>& args)
     : name_(name), classname_(classname), flags_(flags), pid_(0),
-      time_started_(0), time_crashed_(0), nr_crashed_(0), uid_(uid), gid_(gid),
+      crash_count_(0), uid_(uid), gid_(gid),
       supp_gids_(supp_gids), capabilities_(capabilities),
       namespace_flags_(namespace_flags), seclabel_(seclabel),
       ioprio_class_(IoSchedClass_NONE), ioprio_pri_(0), priority_(0),
@@ -190,6 +188,12 @@
     }
 
     property_set(prop_name.c_str(), new_state.c_str());
+
+    if (new_state == "running") {
+        prop_name += ".start";
+        uint64_t start_ns = time_started_.time_since_epoch().count();
+        property_set(prop_name.c_str(), StringPrintf("%" PRIu64, start_ns).c_str());
+    }
 }
 
 void Service::KillProcessGroup(int signal) {
@@ -274,20 +278,19 @@
         return false;
     }
 
-    time_t now = gettime();
+    // If we crash > 4 times in 4 minutes, reboot into recovery.
+    boot_clock::time_point now = boot_clock::now();
     if ((flags_ & SVC_CRITICAL) && !(flags_ & SVC_RESTART)) {
-        if (time_crashed_ + CRITICAL_CRASH_WINDOW >= now) {
-            if (++nr_crashed_ > CRITICAL_CRASH_THRESHOLD) {
-                LOG(ERROR) << "critical process '" << name_ << "' exited "
-                           << CRITICAL_CRASH_THRESHOLD << " times in "
-                           << (CRITICAL_CRASH_WINDOW / 60) << " minutes; "
+        if (now < time_crashed_ + 4min) {
+            if (++crash_count_ > 4) {
+                LOG(ERROR) << "critical process '" << name_ << "' exited 4 times in 4 minutes; "
                            << "rebooting into recovery mode";
                 android_reboot(ANDROID_RB_RESTART2, 0, "recovery");
                 return false;
             }
         } else {
             time_crashed_ = now;
-            nr_crashed_ = 1;
+            crash_count_ = 1;
         }
     }
 
@@ -553,7 +556,6 @@
     // Starting a service removes it from the disabled or reset state and
     // immediately takes it out of the restarting state if it was in there.
     flags_ &= (~(SVC_DISABLED|SVC_RESTARTING|SVC_RESET|SVC_RESTART|SVC_DISABLED_START));
-    time_started_ = 0;
 
     // Running processes require no additional work --- if they're in the
     // process of exiting, we've ensured that they will immediately restart
@@ -667,7 +669,7 @@
         }
     }
 
-    time_started_ = gettime();
+    time_started_ = boot_clock::now();
     pid_ = pid;
     flags_ |= SVC_RUNNING;
 
@@ -731,18 +733,19 @@
     } /* else: Service is restarting anyways. */
 }
 
-void Service::RestartIfNeeded(time_t& process_needs_restart) {
-    time_t next_start_time = time_started_ + 5;
-
-    if (next_start_time <= gettime()) {
+void Service::RestartIfNeeded(time_t* process_needs_restart_at) {
+    boot_clock::time_point now = boot_clock::now();
+    boot_clock::time_point next_start = time_started_ + 5s;
+    if (now > next_start) {
         flags_ &= (~SVC_RESTARTING);
         Start();
         return;
     }
 
-    if ((next_start_time < process_needs_restart) ||
-        (process_needs_restart == 0)) {
-        process_needs_restart = next_start_time;
+    time_t next_start_time_t = time(nullptr) +
+        time_t(std::chrono::duration_cast<std::chrono::seconds>(next_start - now).count());
+    if (next_start_time_t < *process_needs_restart_at || *process_needs_restart_at == 0) {
+        *process_needs_restart_at = next_start_time_t;
     }
 }