Remove the monotonic option for logging

This has been around for ~5 years but there has been roughly no
adoption, so remove this as we clean up the logging code.

Future efforts may track the monotonic timestamp in all cases.

Test: logging unit tests
Change-Id: I55ed565669f923988e741f6b384141bba893630d
diff --git a/liblog/README.md b/liblog/README.md
index f64f376..74a2cd7 100644
--- a/liblog/README.md
+++ b/liblog/README.md
@@ -60,8 +60,6 @@
     LOG_EVENT_INT(tag, value)
     LOG_EVENT_LONG(tag, value)
 
-    clockid_t android_log_clockid()
-
     log_id_t android_logger_get_id(struct logger *logger)
     int android_logger_clear(struct logger *logger)
     int android_logger_get_log_size(struct logger *logger)
@@ -119,7 +117,7 @@
 multiple logs can be opened with `android_logger_list_alloc()`, calling in turn the
 `android_logger_open()` for each log id.  Each entry can be retrieved with
 `android_logger_list_read()`.  The log(s) can be closed with `android_logger_list_free()`.
-`ANDROID_LOG_NONBLOCK` mode will report when the log reading is done with an `EAGAIN` error return 
+`ANDROID_LOG_NONBLOCK` mode will report when the log reading is done with an `EAGAIN` error return
 code, otherwise the `android_logger_list_read()` call will block for new entries.
 
 The `ANDROID_LOG_WRAP` mode flag to the `android_logger_list_alloc_time()` signals logd to quiesce
diff --git a/liblog/include/log/log.h b/liblog/include/log/log.h
index 820b7cb..d7e9b7d 100644
--- a/liblog/include/log/log.h
+++ b/liblog/include/log/log.h
@@ -133,12 +133,6 @@
   (void)__android_log_bswrite(_tag, _value);
 #endif
 
-#ifdef __linux__
-
-clockid_t android_log_clockid(void);
-
-#endif /* __linux__ */
-
 /* --------------------------------------------------------------------- */
 
 /*
diff --git a/liblog/logger_write.cpp b/liblog/logger_write.cpp
index 3a75fa3..22c7eca 100644
--- a/liblog/logger_write.cpp
+++ b/liblog/logger_write.cpp
@@ -192,7 +192,7 @@
     return -EINVAL;
   }
 
-  clock_gettime(android_log_clockid(), &ts);
+  clock_gettime(CLOCK_REALTIME, &ts);
 
   if (log_id == LOG_ID_SECURITY) {
     if (vec[0].iov_len < 4) {
diff --git a/liblog/logprint.cpp b/liblog/logprint.cpp
index 9e8d277..238431f 100644
--- a/liblog/logprint.cpp
+++ b/liblog/logprint.cpp
@@ -216,11 +216,7 @@
   p_ret->year_output = false;
   p_ret->zone_output = false;
   p_ret->epoch_output = false;
-#ifdef __ANDROID__
-  p_ret->monotonic_output = android_log_clockid() == CLOCK_MONOTONIC;
-#else
   p_ret->monotonic_output = false;
-#endif
   p_ret->uid_output = false;
   p_ret->descriptive_output = false;
   descriptive_output = false;
@@ -1465,13 +1461,10 @@
   nsec = entry->tv_nsec;
 #if __ANDROID__
   if (p_format->monotonic_output) {
-    /* prevent convertMonotonic from being called if logd is monotonic */
-    if (android_log_clockid() != CLOCK_MONOTONIC) {
-      struct timespec time;
-      convertMonotonic(&time, entry);
-      now = time.tv_sec;
-      nsec = time.tv_nsec;
-    }
+    struct timespec time;
+    convertMonotonic(&time, entry);
+    now = time.tv_sec;
+    nsec = time.tv_nsec;
   }
 #endif
   if (now < 0) {
diff --git a/liblog/pmsg_writer.cpp b/liblog/pmsg_writer.cpp
index 0751e2c..8e676bd 100644
--- a/liblog/pmsg_writer.cpp
+++ b/liblog/pmsg_writer.cpp
@@ -188,7 +188,7 @@
     return -EINVAL;
   }
 
-  clock_gettime(android_log_clockid(), &ts);
+  clock_gettime(CLOCK_REALTIME, &ts);
 
   cp = strdup(filename);
   if (!cp) {
diff --git a/liblog/properties.cpp b/liblog/properties.cpp
index 37670ec..f5e060c 100644
--- a/liblog/properties.cpp
+++ b/liblog/properties.cpp
@@ -365,29 +365,6 @@
   return c;
 }
 
-static unsigned char evaluate_persist_ro(const struct cache2_char* self) {
-  unsigned char c = self->cache_persist.c;
-
-  if (c) {
-    return c;
-  }
-
-  return self->cache_ro.c;
-}
-
-/*
- * Timestamp state generally remains constant, but can change at any time
- * to handle developer requirements.
- */
-clockid_t android_log_clockid() {
-  static struct cache2_char clockid = {PTHREAD_MUTEX_INITIALIZER, 0,
-                                       "persist.logd.timestamp",  {{NULL, 0xFFFFFFFF}, '\0'},
-                                       "ro.logd.timestamp",       {{NULL, 0xFFFFFFFF}, '\0'},
-                                       evaluate_persist_ro};
-
-  return (tolower(do_cache2_char(&clockid)) == 'm') ? CLOCK_MONOTONIC : CLOCK_REALTIME;
-}
-
 /*
  * Security state generally remains constant, but the DO must be able
  * to turn off logging should it become spammy after an attack is detected.
diff --git a/liblog/tests/liblog_benchmark.cpp b/liblog/tests/liblog_benchmark.cpp
index f4734b9..a4e4def 100644
--- a/liblog/tests/liblog_benchmark.cpp
+++ b/liblog/tests/liblog_benchmark.cpp
@@ -184,7 +184,7 @@
    */
 
   struct timespec ts;
-  clock_gettime(android_log_clockid(), &ts);
+  clock_gettime(CLOCK_REALTIME, &ts);
 
   android_pmsg_log_header_t pmsg_header;
   pmsg_header.magic = LOGGER_MAGIC;
@@ -260,7 +260,7 @@
    */
 
   struct timespec ts;
-  clock_gettime(android_log_clockid(), &ts);
+  clock_gettime(CLOCK_REALTIME, &ts);
 
   struct packet {
     android_pmsg_log_header_t pmsg_header;
@@ -335,7 +335,7 @@
    */
 
   struct timespec ts;
-  clock_gettime(android_log_clockid(), &ts);
+  clock_gettime(CLOCK_REALTIME, &ts);
 
   struct packet {
     android_pmsg_log_header_t pmsg_header;
@@ -410,7 +410,7 @@
    */
 
   struct timespec ts;
-  clock_gettime(android_log_clockid(), &ts);
+  clock_gettime(CLOCK_REALTIME, &ts);
 
   struct packet {
     android_pmsg_log_header_t pmsg_header;
@@ -483,7 +483,7 @@
    */
 
   struct timespec ts;
-  clock_gettime(android_log_clockid(), &ts);
+  clock_gettime(CLOCK_REALTIME, &ts);
 
   struct packet {
     android_pmsg_log_header_t pmsg_header;
@@ -792,16 +792,6 @@
 BENCHMARK(BM_is_loggable);
 
 /*
- *	Measure the time it takes for android_log_clockid.
- */
-static void BM_clockid(benchmark::State& state) {
-  while (state.KeepRunning()) {
-    android_log_clockid();
-  }
-}
-BENCHMARK(BM_clockid);
-
-/*
  *	Measure the time it takes for __android_log_security.
  */
 static void BM_security(benchmark::State& state) {
diff --git a/liblog/tests/liblog_test.cpp b/liblog/tests/liblog_test.cpp
index d3d8e91..bbc985a 100644
--- a/liblog/tests/liblog_test.cpp
+++ b/liblog/tests/liblog_test.cpp
@@ -329,8 +329,6 @@
 #ifdef __ANDROID__
   pid_t pid = getpid();
 
-  log_time ts(android_log_clockid());
-
   size_t num_lines = 1, size = 0, length = 0, total = 0;
   const char* cp = message;
   while (*cp) {
@@ -432,7 +430,6 @@
   pid_t pid = getpid();
 
   static const char tag[] = "TEST__android_log_buf_write";
-  log_time ts(android_log_clockid());
 
   auto write_function = [&] {
     EXPECT_LT(0, __android_log_buf_write(LOG_ID_MAIN, ANDROID_LOG_INFO, tag, message));