logd: don't use SIGHUP to reinitialize

It doesn't look like there are any users, since there is a much better
mechanism, `logd --reinit` that exists for this behavior.  The
settings app and init.rc use that mechanism and they are the two major
clients that force logd to reinitialize.

This saves us from creating a thread and marginally cleans up
main.cpp.

Test: log reinitialization works
Change-Id: Icdb56b6f59adbba82812231a4f3a6ffd1a7955fc
diff --git a/logd/CommandListener.cpp b/logd/CommandListener.cpp
index 1e7a33a..4b94086 100644
--- a/logd/CommandListener.cpp
+++ b/logd/CommandListener.cpp
@@ -31,6 +31,7 @@
 
 #include <android-base/stringprintf.h>
 #include <cutils/sockets.h>
+#include <log/log_properties.h>
 #include <private/android_filesystem_config.h>
 #include <sysutils/SocketClient.h>
 
@@ -296,7 +297,20 @@
                                            char** /*argv*/) {
     setname();
 
-    reinit_signal_handler(SIGHUP);
+    android::prdebug("logd reinit");
+    buf()->init();
+    buf()->initPrune(nullptr);
+
+    // This only works on userdebug and eng devices to re-read the
+    // /data/misc/logd/event-log-tags file right after /data is mounted.
+    // The operation is near to boot and should only happen once.  There
+    // are races associated with its use since it can trigger a Rebuild
+    // of the file, but that is a can-not-happen since the file was not
+    // read yet.  More dangerous if called later, but if all is well it
+    // should just skip over everything and not write any new entries.
+    if (__android_log_is_debuggable()) {
+        tags()->ReadFileEventLogTags(tags()->debug_event_log_tags);
+    }
 
     cli->sendMsg("success");
 
diff --git a/logd/CommandListener.h b/logd/CommandListener.h
index 80597b2..c50ab6e 100644
--- a/logd/CommandListener.h
+++ b/logd/CommandListener.h
@@ -24,9 +24,6 @@
 #include "LogReader.h"
 #include "LogTags.h"
 
-// See main.cpp for implementation
-void reinit_signal_handler(int /*signal*/);
-
 class CommandListener : public FrameworkListener {
   public:
     CommandListener(LogBuffer* buf, LogTags* tags);
diff --git a/logd/LogBuffer.cpp b/logd/LogBuffer.cpp
index 443fd98..7e1bb0a 100644
--- a/logd/LogBuffer.cpp
+++ b/logd/LogBuffer.cpp
@@ -92,11 +92,7 @@
         unlock();
     }
 
-    // We may have been triggered by a SIGHUP. Release any sleeping reader
-    // threads to dump their current content.
-    //
-    // NB: this is _not_ performed in the context of a SIGHUP, it is
-    // performed during startup, and in context of reinit administrative thread
+    // Release any sleeping reader threads to dump their current content.
     LogTimeEntry::wrlock();
 
     LastLogTimes::iterator times = mTimes.begin();
diff --git a/logd/LogTags.cpp b/logd/LogTags.cpp
index e45cc8a..3e52b38 100644
--- a/logd/LogTags.cpp
+++ b/logd/LogTags.cpp
@@ -391,23 +391,6 @@
     return me->tagToName(tag);
 }
 
-// Prototype in LogUtils.h allowing external access to our database.
-//
-// This only works on userdebug and eng devices to re-read the
-// /data/misc/logd/event-log-tags file right after /data is mounted.
-// The operation is near to boot and should only happen once.  There
-// are races associated with its use since it can trigger a Rebuild
-// of the file, but that is a can-not-happen since the file was not
-// read yet.  More dangerous if called later, but if all is well it
-// should just skip over everything and not write any new entries.
-void android::ReReadEventLogTags() {
-    LogTags* me = logtags;
-
-    if (me && __android_log_is_debuggable()) {
-        me->ReadFileEventLogTags(me->debug_event_log_tags);
-    }
-}
-
 // converts an event tag into a format
 const char* LogTags::tagToFormat(uint32_t tag) const {
     tag2format_const_iterator iform;
diff --git a/logd/LogUtils.h b/logd/LogUtils.h
index fa9f398..f9cd42d 100644
--- a/logd/LogUtils.h
+++ b/logd/LogUtils.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef _LOGD_LOG_UTILS_H__
-#define _LOGD_LOG_UTILS_H__
+#pragma once
 
 #include <sys/cdefs.h>
 #include <sys/types.h>
@@ -41,7 +40,6 @@
 
 // Furnished in LogTags.cpp. Thread safe.
 const char* tagToName(uint32_t tag);
-void ReReadEventLogTags();
 
 // Furnished by LogKlog.cpp
 char* log_strntok_r(char* s, ssize_t& len, char*& saveptr, ssize_t& sublen);
@@ -72,5 +70,3 @@
     return (id == LOG_ID_MAIN) || (id == LOG_ID_SYSTEM) ||
            (id == LOG_ID_RADIO) || (id == LOG_ID_EVENTS);
 }
-
-#endif  // _LOGD_LOG_UTILS_H__
diff --git a/logd/main.cpp b/logd/main.cpp
index 8713147..c4750ec 100644
--- a/logd/main.cpp
+++ b/logd/main.cpp
@@ -151,50 +151,6 @@
     }
 }
 
-static sem_t reinit;
-static bool reinit_running = false;
-static LogBuffer* logBuf = nullptr;
-
-static void* reinit_thread_start(void* /*obj*/) {
-    prctl(PR_SET_NAME, "logd.daemon");
-
-    while (reinit_running && !sem_wait(&reinit) && reinit_running) {
-        if (fdDmesg >= 0) {
-            static const char reinit_message[] = { KMSG_PRIORITY(LOG_INFO),
-                                                   'l',
-                                                   'o',
-                                                   'g',
-                                                   'd',
-                                                   '.',
-                                                   'd',
-                                                   'a',
-                                                   'e',
-                                                   'm',
-                                                   'o',
-                                                   'n',
-                                                   ':',
-                                                   ' ',
-                                                   'r',
-                                                   'e',
-                                                   'i',
-                                                   'n',
-                                                   'i',
-                                                   't',
-                                                   '\n' };
-            write(fdDmesg, reinit_message, sizeof(reinit_message));
-        }
-
-        // Anything that reads persist.<property>
-        if (logBuf) {
-            logBuf->init();
-            logBuf->initPrune(nullptr);
-        }
-        android::ReReadEventLogTags();
-    }
-
-    return nullptr;
-}
-
 char* android::uidToName(uid_t u) {
     struct Userdata {
         uid_t uid;
@@ -221,12 +177,6 @@
     return userdata.name;
 }
 
-// Serves as a global method to trigger reinitialization
-// and as a function that can be provided to signal().
-void reinit_signal_handler(int /*signal*/) {
-    sem_post(&reinit);
-}
-
 static void readDmesg(LogAudit* al, LogKlog* kl) {
     if (!al && !kl) {
         return;
@@ -337,25 +287,6 @@
         return EXIT_FAILURE;
     }
 
-    // Reinit Thread
-    sem_init(&reinit, 0, 0);
-    pthread_attr_t attr;
-    if (!pthread_attr_init(&attr)) {
-        struct sched_param param;
-
-        memset(&param, 0, sizeof(param));
-        pthread_attr_setschedparam(&attr, &param);
-        pthread_attr_setschedpolicy(&attr, SCHED_BATCH);
-        if (!pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED)) {
-            pthread_t thread;
-            reinit_running = true;
-            if (pthread_create(&thread, &attr, reinit_thread_start, nullptr)) {
-                reinit_running = false;
-            }
-        }
-        pthread_attr_destroy(&attr);
-    }
-
     // A cache of event log tags
     LogTags log_tags;
 
@@ -368,9 +299,7 @@
     // LogBuffer is the object which is responsible for holding all
     // log entries.
 
-    logBuf = new LogBuffer(times, &log_tags);
-
-    signal(SIGHUP, reinit_signal_handler);
+    LogBuffer* logBuf = new LogBuffer(times, &log_tags);
 
     if (__android_logger_property_get_bool(
             "logd.statistics", BOOL_DEFAULT_TRUE | BOOL_DEFAULT_FLAG_PERSIST |