[alohalytics] Renaming and better documentation for MessagesQueue.

3party/Alohalytics/src/messages_queue.h

@@ -22,6 +22,11 @@ OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 SOFTWARE.
 *******************************************************************************/
 
+// This queue stores incoming messages in the memory on a separate thread as a continuous
+// block of bytes. If storage directory is set, it stores everything in a file (on a separate thread too).
+// When TMaxFileSizeInBytes limit is hit, file is "archived" (see TFileArchiver in constructor)
+// and a new file is created instead.
+
 #ifndef MESSAGES_QUEUE_H
 #define MESSAGES_QUEUE_H
 
@@ -37,7 +42,7 @@ SOFTWARE.
 #include <string>              // string
 #include <thread>              // thread
 
-#include "file_manager.h"  // ForEachFileInDir
+#include "file_manager.h"
 
 namespace alohalytics {
 
@@ -45,7 +50,7 @@ namespace alohalytics {
 typedef std::function<void(const std::string & file_to_archive, const std::string & archived_file)> TFileArchiver;
 // Processor should return true if file was processed successfully.
 // If file_name_in_content is true, then second parameter is a full path to a file instead of a buffer.
-typedef std::function<bool(bool file_name_in_content, const std::string & content)> TArchivedFileProcessor;
+typedef std::function<bool(bool file_name_in_content, const std::string & content)> TArchivedFilesProcessor;
 enum class ProcessingResult { EProcessedSuccessfully, EProcessingError, ENothingToProcess };
 typedef std::function<void(ProcessingResult)> TFileProcessingFinishedCallback;
 
@@ -99,8 +104,9 @@ class MessagesQueue final {
   // File is deleted if processor has returned true.
   // Processing stops if processor returns false.
   // Optional callback is called when all files are processed.
+  // This call automatically archives current file before processing, but zero-sized "current" file is never archived.
   // Executed on the WorkerThread.
-  void ProcessArchivedFiles(TArchivedFileProcessor processor,
+  void ProcessArchivedFiles(TArchivedFilesProcessor processor,
                             TFileProcessingFinishedCallback callback = TFileProcessingFinishedCallback()) {
     std::lock_guard<std::mutex> lock(mutex_);
     commands_queue_.push_back(std::bind(&MessagesQueue::ProcessArchivedFilesCommand, this, processor, callback));
@@ -137,7 +143,7 @@ class MessagesQueue final {
         ArchiveCurrentFile();
       }
     } else {
-      messages_storage_.append(messages_buffer);
+      inmemory_storage_.append(messages_buffer);
     }
   }
 
@@ -153,9 +159,9 @@ class MessagesQueue final {
       storage_directory_ = directory;
       current_file_ = std::move(new_current_file);
       // Also check if there are any messages in the memory storage, and save them to file.
-      if (!messages_storage_.empty()) {
-        StoreMessages(messages_storage_);
-        messages_storage_.clear();
+      if (!inmemory_storage_.empty()) {
+        StoreMessages(inmemory_storage_);
+        inmemory_storage_.clear();
       }
     }
   }
@@ -174,12 +180,12 @@ class MessagesQueue final {
   }
 
   // If there is no file storage directory set, it should also process messages from the memory buffer.
-  void ProcessArchivedFilesCommand(TArchivedFileProcessor processor, TFileProcessingFinishedCallback callback) {
+  void ProcessArchivedFilesCommand(TArchivedFilesProcessor processor, TFileProcessingFinishedCallback callback) {
     ProcessingResult result = ProcessingResult::ENothingToProcess;
     // Process in-memory messages, if any.
-    if (!messages_storage_.empty()) {
-      if (processor(false /* in-memory buffer */, messages_storage_)) {
-        messages_storage_.clear();
+    if (!inmemory_storage_.empty()) {
+      if (processor(false /* in-memory buffer */, inmemory_storage_)) {
+        inmemory_storage_.clear();
         result = ProcessingResult::EProcessedSuccessfully;
       } else {
         result = ProcessingResult::EProcessingError;
@@ -241,7 +247,7 @@ class MessagesQueue final {
   // Directory with a slash at the end, where we store "current" file and archived files.
   std::string storage_directory_;
   // Used as an in-memory storage if storage_dir_ was not set.
-  std::string messages_storage_;
+  std::string inmemory_storage_;
   typedef std::function<void()> TCommand;
   std::list<TCommand> commands_queue_;