logd: initial checkin.

* Create a new userspace log daemon for handling logging messages.

Original-Change-Id: I75267df16359684490121e6c31cca48614d79856
Signed-off-by: Nick Kralevich <nnk@google.com>

* Merge conflicts
* rename new syslog daemon to logd to prevent confusion with bionic syslog
* replace racy getGroups call with KISS call to client->getGid()
* Timestamps are filed at logging source
* insert entries into list in timestamp order
* Added LogTimeEntry tail filtration handling
* Added region locking around LogWriter list
* separate threads for each writer
* /dev/socket/logd* permissions

Signed-off-by: Mark Salyzyn <salyzyn@google.com>

(cherry picked from commit 3e76e0a49760c4970b7cda6153e51026af98e4f3)

Author: Nick Kralevich <nnk@google.com>
Change-Id: Ice88b1412d8f9daa7f9119b2b5aaf684a5e28098
diff --git a/logd/LogTimes.h b/logd/LogTimes.h
new file mode 100644
index 0000000..ac52db2
--- /dev/null
+++ b/logd/LogTimes.h
@@ -0,0 +1,108 @@
+/*
+ * Copyright (C) 2012-2013 The Android Open Source Project
+ *
+ * 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.
+ */
+
+#ifndef _LOGD_LOG_TIMES_H__
+#define _LOGD_LOG_TIMES_H__
+
+#include <pthread.h>
+#include <time.h>
+#include <sys/types.h>
+#include <sysutils/SocketClient.h>
+#include <utils/List.h>
+
+class LogReader;
+
+class LogTimeEntry {
+    static pthread_mutex_t timesLock;
+    unsigned int mRefCount;
+    bool mRelease;
+    bool mError;
+    bool threadRunning;
+    bool threadTriggered;
+    pthread_t mThread;
+    LogReader &mReader;
+    static void *threadStart(void *me);
+    static void threadStop(void *me);
+    const unsigned int mLogMask;
+    const pid_t mPid;
+    unsigned int skipAhead;
+    unsigned long mCount;
+    unsigned long mTail;
+    unsigned long mIndex;
+
+public:
+    LogTimeEntry(LogReader &reader, SocketClient *client, bool nonBlock,
+                 unsigned long tail, unsigned int logMask, pid_t pid);
+
+    SocketClient *mClient;
+    static const struct timespec EPOCH;
+    log_time mStart;
+    const bool mNonBlock;
+    const log_time mEnd; // only relevant if mNonBlock
+
+    // Protect List manipulations
+    static void lock(void) { pthread_mutex_lock(&timesLock); }
+    static void unlock(void) { pthread_mutex_unlock(&timesLock); }
+
+    void startReader_Locked(void);
+
+    bool runningReader_Locked(void) const
+    {
+        return threadRunning || mRelease || mError || mNonBlock;
+    }
+    void triggerReader_Locked(void) { threadTriggered = true; }
+    void triggerSkip_Locked(unsigned int skip) { skipAhead = skip; }
+
+    // Called after LogTimeEntry removed from list, lock implicitly held
+    void release_Locked(void)
+    {
+        mRelease = true;
+        if (mRefCount || threadRunning) {
+            return;
+        }
+        // No one else is holding a reference to this
+        delete this;
+    }
+
+    // Called to mark socket in jeopardy
+    void error_Locked(void) { mError = true; }
+    void error(void) { lock(); mError = true; unlock(); }
+
+    bool isError_Locked(void) const { return mRelease || mError; }
+
+    // Mark Used
+    //  Locking implied, grabbed when protection around loop iteration
+    void incRef_Locked(void) { ++mRefCount; }
+
+    bool owned_Locked(void) const { return mRefCount != 0; }
+
+    void decRef_Locked(void)
+    {
+        if ((mRefCount && --mRefCount) || !mRelease || threadRunning) {
+            return;
+        }
+        // No one else is holding a reference to this
+        delete this;
+    }
+
+    // flushTo filter callbacks
+    static bool FilterFirstPass(const LogBufferElement *element, void *me);
+    static bool FilterSecondPass(const LogBufferElement *element, void *me);
+};
+
+typedef android::List<LogTimeEntry *> LastLogTimes;
+
+#endif