SERVER-10084 New logging implementation.

This change-set:

* Introduces a new top-level directory, mongo/logger, containing most of the implementation of logging functionality formerly found in log.cpp/log.h.

* Cleans up existing, unusual uses of the logging system that were not trivially compatible with the new implementation.

* Replaces Logstream/Nulstream with a LogstreamBuilder object, whose destructor writes log messages.  This new LogstreamBuilder is reentrant, unlike the old logging code, which was thread-safe but not reentrant.  Additionally, std::endl is no longer required to terminate a log line.  When a LogstreamBuilder goes out of scope, the log message gets committed.

* Separates the log system into several components: a global LogManager, several LogDomains, various kinds of Appenders (e.g., SyslogAppender) and Encoders (for formatting messages).

* Allows unit tests to capture and examine log output.

This patch does _not_ introduce support for hierarchical log domains, or for enabling and disabling specific log domains when the server is running in a multi-threaded mode.  This is future work.

1 files changed, 61 insertions, 0 deletions

diff --git a/src/mongo/logger/rotatable_file_appender.h b/src/mongo/logger/rotatable_file_appender.h
new file mode 100644
index 00000000000..32384011280
--- /dev/null
+++ b/src/mongo/logger/rotatable_file_appender.h
@@ -0,0 +1,61 @@
+/*    Copyright 2013 10gen Inc.
+ *
+ *    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.
+ */
+
+#pragma once
+
+#include "mongo/base/disallow_copying.h"
+#include "mongo/base/status.h"
+#include "mongo/logger/appender.h"
+#include "mongo/logger/encoder.h"
+#include "mongo/logger/rotatable_file_writer.h"
+
+namespace mongo {
+namespace logger {
+
+    /**
+     * Appender for writing to instances of RotatableFileWriter.
+     */
+    template <typename Event>
+    class RotatableFileAppender : public Appender<Event> {
+        MONGO_DISALLOW_COPYING(RotatableFileAppender);
+
+    public:
+        typedef Encoder<Event> EventEncoder;
+
+        /**
+         * Constructs an appender, that owns "encoder", but not "writer."  Caller must
+         * keep "writer" in scope at least as long as the constructed appender.
+         */
+        RotatableFileAppender(EventEncoder* encoder, RotatableFileWriter* writer) :
+            _encoder(encoder),
+            _writer(writer) {
+        }
+
+        virtual Status append(const Event& event) {
+            RotatableFileWriter::Use useWriter(_writer);
+            Status status = useWriter.status();
+            if (!status.isOK())
+                return status;
+            _encoder->encode(event, useWriter.stream()).flush();
+            return useWriter.status();
+        }
+
+    private:
+        boost::scoped_ptr<EventEncoder> _encoder;
+        RotatableFileWriter* _writer;
+    };
+
+}  // namespace logger
+}  // namespace mongo