FLOG: Add examples/flog_viewer and always show MOJO_DLOG messages

services/flog/flog_logger_impl.cc

Index: services/flog/flog_logger_impl.cc
diff --git a/services/flog/flog_logger_impl.cc b/services/flog/flog_logger_impl.cc
index 6941e0dc9c6752689176efd29d757c6cf1113326..d870f99c1b73b87ec98f932dc8d092c194bf1574 100644
--- a/services/flog/flog_logger_impl.cc
+++ b/services/flog/flog_logger_impl.cc
@@ -2,12 +2,50 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+#include <iomanip>
+#include <iostream>
+
 #include "base/logging.h"
 #include "services/flog/flog_logger_impl.h"
 
 namespace mojo {
 namespace flog {
 
+namespace {
+
+struct AsMicroseconds {
+  explicit AsMicroseconds(uint64_t time_us) : time_us_(time_us) {}
+  uint64_t time_us_;
+};
+
+std::ostream& operator<<(std::ostream& os, AsMicroseconds value) {
+  return os << std::setfill('0') << std::setw(6) << value.time_us_ % 1000000ull;
+}
+
+struct AsLogLevel {
+  explicit AsLogLevel(uint32_t level) : level_(level) {}
+  uint32_t level_;
+};
+
+std::ostream& operator<<(std::ostream& os, AsLogLevel value) {
+  switch (value.level_) {
+    case MOJO_LOG_LEVEL_VERBOSE:
+      return os << "VERBOSE";
+    case MOJO_LOG_LEVEL_INFO:
+      return os << "INFO";
+    case MOJO_LOG_LEVEL_WARNING:
+      return os << "WARNING";
+    case MOJO_LOG_LEVEL_ERROR:
+      return os << "ERROR";
+    case MOJO_LOG_LEVEL_FATAL:
+      return os << "FATAL";
+    default:
+      return os << "UNKNOWN LEVEL " << value.level_;
+  }
+}
+
+}  // namespace
+
 // static
 std::shared_ptr<FlogLoggerImpl> FlogLoggerImpl::Create(
     InterfaceRequest<FlogLogger> request,
@@ -32,6 +70,7 @@ FlogLoggerImpl::FlogLoggerImpl(InterfaceRequest<FlogLogger> request,
       Environment::GetDefaultAsyncWaiter()));
   router_->set_incoming_receiver(this);
   router_->set_connection_error_handler([this]() { ReleaseFromOwner(); });
+  stub_.set_sink(this);
 }
 
 FlogLoggerImpl::~FlogLoggerImpl() {}
@@ -46,6 +85,12 @@ bool FlogLoggerImpl::Accept(Message* message) {
   WriteData(sizeof(message_size), &message_size);
   WriteData(message_size, message->data());
 
+  // Call the stub to output mojo logger messages to stderr. This has to
+  // happen after we write the message to the file, because deserialization
+  // mutates the message.
+  // TODO(dalesat): Provide a switch to turn this off.
+  stub_.Accept(message);
+
   return true;
 }
 
@@ -70,5 +115,24 @@ void FlogLoggerImpl::WriteData(uint32_t data_size, const void* data) {
                });
 }
 
+void FlogLoggerImpl::LogMojoLoggerMessage(int64_t time_us,
+                                          int32_t log_level,
+                                          const String& message,
+                                          const String& source_file,
+                                          uint32_t source_line) {
+  std::cerr << AsMicroseconds(time_us) << " " << AsLogLevel(log_level) << ":"
+            << source_file << "#" << source_line << " " << message << std::endl;
+}
+
+void FlogLoggerImpl::LogChannelCreation(int64_t time_us,
+                                        uint32_t channel_id,
+                                        const String& type_name) {}
+
+void FlogLoggerImpl::LogChannelMessage(int64_t time_us,
+                                       uint32_t channel_id,
+                                       mojo::Array<uint8_t> data) {}
+
+void FlogLoggerImpl::LogChannelDeletion(int64_t time_us, uint32_t channel_id) {}
+
 }  // namespace flog
 }  // namespace mojo