logd: make LogBuffer an interface

We may use different implementations of LogBuffer in the future, so we
make it interface and create a concrete ChattyLogBuffer class that
implements it.

Test: logging unit tests
Change-Id: I5731d6404640664c9acc26b7c677dff3110c6a11
diff --git a/logd/LogBuffer.h b/logd/LogBuffer.h
index efcd2af..887e5f0 100644
--- a/logd/LogBuffer.h
+++ b/logd/LogBuffer.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2012-2014 The Android Open Source Project
+ * Copyright (C) 2020 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.
@@ -18,23 +18,12 @@
 
 #include <sys/types.h>
 
-#include <list>
-#include <optional>
-#include <string>
+#include <functional>
 
-#include <android/log.h>
-#include <private/android_filesystem_config.h>
+#include <log/log.h>
 #include <sysutils/SocketClient.h>
 
 #include "LogBufferElement.h"
-#include "LogStatistics.h"
-#include "LogTags.h"
-#include "LogWhiteBlackList.h"
-
-typedef std::list<LogBufferElement*> LogBufferElementCollection;
-
-class LogReaderList;
-class LogReaderThread;
 
 enum class FlushToResult {
     kSkip,
@@ -43,71 +32,23 @@
 };
 
 class LogBuffer {
-    LogBufferElementCollection mLogElements;
-    pthread_rwlock_t mLogElementsLock;
-
-    // watermark of any worst/chatty uid processing
-    typedef std::unordered_map<uid_t, LogBufferElementCollection::iterator>
-        LogBufferIteratorMap;
-    LogBufferIteratorMap mLastWorst[LOG_ID_MAX];
-    // watermark of any worst/chatty pid of system processing
-    typedef std::unordered_map<pid_t, LogBufferElementCollection::iterator>
-        LogBufferPidIteratorMap;
-    LogBufferPidIteratorMap mLastWorstPidOfSystem[LOG_ID_MAX];
-
-    unsigned long mMaxSize[LOG_ID_MAX];
-
-    LogBufferElement* lastLoggedElements[LOG_ID_MAX];
-    LogBufferElement* droppedElements[LOG_ID_MAX];
-    void log(LogBufferElement* elem);
-
   public:
-    LogBuffer(LogReaderList* reader_list, LogTags* tags, PruneList* prune, LogStatistics* stats);
-    ~LogBuffer();
-    void init();
+    virtual ~LogBuffer() {}
 
-    int log(log_id_t log_id, log_time realtime, uid_t uid, pid_t pid, pid_t tid, const char* msg,
-            uint16_t len);
+    virtual void Init() = 0;
+
+    virtual int Log(log_id_t log_id, log_time realtime, uid_t uid, pid_t pid, pid_t tid,
+                    const char* msg, uint16_t len) = 0;
     // lastTid is an optional context to help detect if the last previous
     // valid message was from the same source so we can differentiate chatty
     // filter types (identical or expired)
-    uint64_t flushTo(SocketClient* writer, uint64_t start,
-                     pid_t* lastTid,  // &lastTid[LOG_ID_MAX] or nullptr
-                     bool privileged, bool security,
-                     const std::function<FlushToResult(const LogBufferElement* element)>& filter);
+    virtual uint64_t FlushTo(
+            SocketClient* writer, uint64_t start,
+            pid_t* last_tid,  // nullable
+            bool privileged, bool security,
+            const std::function<FlushToResult(const LogBufferElement* element)>& filter) = 0;
 
-    bool clear(log_id_t id, uid_t uid = AID_ROOT);
-    unsigned long getSize(log_id_t id);
-    int setSize(log_id_t id, unsigned long size);
-
-  private:
-    void wrlock() {
-        pthread_rwlock_wrlock(&mLogElementsLock);
-    }
-    void rdlock() {
-        pthread_rwlock_rdlock(&mLogElementsLock);
-    }
-    void unlock() {
-        pthread_rwlock_unlock(&mLogElementsLock);
-    }
-
-    void maybePrune(log_id_t id);
-    void kickMe(LogReaderThread* me, log_id_t id, unsigned long pruneRows);
-
-    bool prune(log_id_t id, unsigned long pruneRows, uid_t uid = AID_ROOT);
-    LogBufferElementCollection::iterator erase(
-        LogBufferElementCollection::iterator it, bool coalesce = false);
-
-    // Returns an iterator to the oldest element for a given log type, or mLogElements.end() if
-    // there are no logs for the given log type. Requires mLogElementsLock to be held.
-    LogBufferElementCollection::iterator GetOldest(log_id_t log_id);
-
-    LogReaderList* reader_list_;
-    LogTags* tags_;
-    PruneList* prune_;
-    LogStatistics* stats_;
-
-    // Keeps track of the iterator to the oldest log message of a given log type, as an
-    // optimization when pruning logs.  Use GetOldest() to retrieve.
-    std::optional<LogBufferElementCollection::iterator> oldest_[LOG_ID_MAX];
-};
+    virtual bool Clear(log_id_t id, uid_t uid) = 0;
+    virtual unsigned long GetSize(log_id_t id) = 0;
+    virtual int SetSize(log_id_t id, unsigned long size) = 0;
+};
\ No newline at end of file