logging: add a FileHandlerFactory class
authorAdam Simpkins <simpkins@fb.com>
Wed, 29 Nov 2017 01:44:55 +0000 (17:44 -0800)
committerFacebook Github Bot <facebook-github-bot@users.noreply.github.com>
Wed, 29 Nov 2017 01:52:55 +0000 (17:52 -0800)
Summary:
Add a new LogHandlerFactory interface for creating LogHandler objects from a
LogHandlerConfig.

Also add an initial FileHandlerFactory implementation capable of creating
LogHandler objects that write to a file descriptor.

Reviewed By: bolinfest

Differential Revision: D6200567

fbshipit-source-id: 14b86fc14ad475223aa4b57d45c40638b48c7594

CMakeLists.txt
folly/Makefile.am
folly/experimental/logging/AsyncFileWriter.cpp
folly/experimental/logging/AsyncFileWriter.h
folly/experimental/logging/FileHandlerFactory.cpp [new file with mode: 0644]
folly/experimental/logging/FileHandlerFactory.h [new file with mode: 0644]
folly/experimental/logging/ImmediateFileWriter.h
folly/experimental/logging/LogHandlerFactory.h [new file with mode: 0644]
folly/experimental/logging/Makefile.am
folly/experimental/logging/StandardLogHandler.h
folly/experimental/logging/test/FileHandlerFactoryTest.cpp [new file with mode: 0644]

index ec5a985..8669d26 100755 (executable)
@@ -386,6 +386,7 @@ if (BUILD_TESTS)
     DIRECTORY experimental/logging/test/
       TEST async_file_writer_test SOURCES AsyncFileWriterTest.cpp
       TEST config_parser_test SOURCES ConfigParserTest.cpp
+      TEST file_handler_factory_test SOURCES FileHandlerFactoryTest.cpp
       TEST glog_formatter_test SOURCES GlogFormatterTest.cpp
       TEST immediate_file_writer_test SOURCES ImmediateFileWriterTest.cpp
       TEST log_category_test SOURCES LogCategoryTest.cpp
index 5c60a72..a1c508b 100644 (file)
@@ -156,6 +156,7 @@ nobase_follyinclude_HEADERS = \
        experimental/JSONSchema.h \
        experimental/LockFreeRingBuffer.h \
        experimental/logging/AsyncFileWriter.h \
+       experimental/logging/FileHandlerFactory.h \
        experimental/logging/GlogStyleFormatter.h \
        experimental/logging/ImmediateFileWriter.h \
        experimental/logging/Init.h \
@@ -167,6 +168,7 @@ nobase_follyinclude_HEADERS = \
        experimental/logging/Logger.h \
        experimental/logging/LoggerDB.h \
        experimental/logging/LogHandler.h \
+       experimental/logging/LogHandlerFactory.h \
        experimental/logging/LogHandlerConfig.h \
        experimental/logging/LogLevel.h \
        experimental/logging/LogMessage.h \
index fbd0641..18895ff 100644 (file)
@@ -25,6 +25,8 @@ using folly::StringPiece;
 
 namespace folly {
 
+constexpr size_t AsyncFileWriter::kDefaultMaxBufferSize;
+
 AsyncFileWriter::AsyncFileWriter(StringPiece path)
     : AsyncFileWriter{File{path.str(), O_WRONLY | O_APPEND | O_CREAT}} {}
 
@@ -80,6 +82,16 @@ void AsyncFileWriter::flush() {
   }
 }
 
+void AsyncFileWriter::setMaxBufferSize(size_t size) {
+  auto data = data_.lock();
+  data->maxBufferBytes = size;
+}
+
+size_t AsyncFileWriter::getMaxBufferSize() const {
+  auto data = data_.lock();
+  return data->maxBufferBytes;
+}
+
 void AsyncFileWriter::ioThread() {
   folly::setThreadName("log_writer");
 
index 4fdd24e..824b3c5 100644 (file)
@@ -43,6 +43,13 @@ namespace folly {
  */
 class AsyncFileWriter : public LogWriter {
  public:
+  /**
+   * The default maximum buffer size.
+   *
+   * The comments for setMaxBufferSize() explain how this parameter is used.
+   */
+  static constexpr size_t kDefaultMaxBufferSize = 1024 * 1024;
+
   /**
    * Construct an AsyncFileWriter that appends to the file at the specified
    * path.
@@ -65,6 +72,28 @@ class AsyncFileWriter : public LogWriter {
    */
   void flush() override;
 
+  /**
+   * Set the maximum buffer size for this AsyncFileWriter, in bytes.
+   *
+   * This controls the upper bound on how much unwritten data will be buffered
+   * in memory.  If messages are being logged faster than they can be written
+   * to output file, new messages will be discarded if they would cause the
+   * amount of buffered data to exceed this limit.
+   */
+  void setMaxBufferSize(size_t size);
+
+  /**
+   * Get the maximum buffer size for this AsyncFileWriter, in bytes.
+   */
+  size_t getMaxBufferSize() const;
+
+  /**
+   * Get the output file.
+   */
+  const folly::File& getFile() const {
+    return file_;
+  }
+
  private:
   /*
    * A simple implementation using two queues.
@@ -79,7 +108,7 @@ class AsyncFileWriter : public LogWriter {
     bool stop{false};
     bool ioThreadDone{false};
     uint64_t ioThreadCounter{0};
-    size_t maxBufferBytes{1024 * 1024};
+    size_t maxBufferBytes{kDefaultMaxBufferSize};
     size_t currentBufferSize{0};
     size_t numDiscarded{0};
 
diff --git a/folly/experimental/logging/FileHandlerFactory.cpp b/folly/experimental/logging/FileHandlerFactory.cpp
new file mode 100644 (file)
index 0000000..43d3a18
--- /dev/null
@@ -0,0 +1,125 @@
+/*
+ * Copyright 2004-present Facebook, 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.
+ */
+#include <folly/experimental/logging/FileHandlerFactory.h>
+
+#include <set>
+
+#include <folly/Conv.h>
+#include <folly/MapUtil.h>
+#include <folly/experimental/logging/AsyncFileWriter.h>
+#include <folly/experimental/logging/GlogStyleFormatter.h>
+#include <folly/experimental/logging/ImmediateFileWriter.h>
+#include <folly/experimental/logging/StandardLogHandler.h>
+
+using std::make_shared;
+using std::shared_ptr;
+using std::string;
+
+namespace folly {
+
+std::shared_ptr<LogHandler> FileHandlerFactory::createHandler(
+    const Options& options) {
+  // Raise an error if we receive unexpected options
+  auto knownOptions =
+      std::set<std::string>{"path", "stream", "async", "max_buffer_size"};
+  for (const auto& entry : options) {
+    if (knownOptions.find(entry.first) == knownOptions.end()) {
+      throw std::invalid_argument(to<string>(
+          "unknown parameter \"", entry.first, "\" for FileHandlerFactory"));
+    }
+  }
+
+  // Construct the formatter
+  // TODO: We should eventually support parameters to control the formatter
+  // behavior.
+  auto formatter = make_shared<GlogStyleFormatter>();
+
+  // Get the output file to use
+  File outputFile;
+  auto* path = get_ptr(options, "path");
+  auto* stream = get_ptr(options, "stream");
+  if (path && stream) {
+    throw std::invalid_argument(
+        "cannot specify both \"path\" and \"stream\" "
+        "parameters for FileHandlerFactory");
+  } else if (path) {
+    outputFile = File{*path, O_WRONLY | O_APPEND | O_CREAT};
+  } else if (stream) {
+    if (*stream == "stderr") {
+      outputFile = File{STDERR_FILENO, /* ownsFd */ false};
+    } else if (*stream == "stdout") {
+      outputFile = File{STDOUT_FILENO, /* ownsFd */ false};
+    } else {
+      throw std::invalid_argument(to<string>(
+          "unknown stream for FileHandlerFactory: \"",
+          *stream,
+          "\" expected one of stdout or stderr"));
+    }
+  } else {
+    throw std::invalid_argument(
+        "must specify a \"path\" or \"stream\" "
+        "parameter for FileHandlerFactory");
+  }
+
+  // Determine whether we should use ImmediateFileWriter or AsyncFileWriter
+  shared_ptr<LogWriter> writer;
+  bool async = true;
+  auto* asyncOption = get_ptr(options, "async");
+  if (asyncOption) {
+    try {
+      async = to<bool>(*asyncOption);
+    } catch (const std::exception& ex) {
+      throw std::invalid_argument(to<string>(
+          "expected a boolean value for FileHandlerFactory \"async\" "
+          "parameter: ",
+          *asyncOption));
+    }
+  }
+  auto* maxBufferOption = get_ptr(options, "max_buffer_size");
+  if (async) {
+    auto asyncWriter = make_shared<AsyncFileWriter>(std::move(outputFile));
+    if (maxBufferOption) {
+      size_t maxBufferSize;
+      try {
+        maxBufferSize = to<size_t>(*maxBufferOption);
+      } catch (const std::exception& ex) {
+        throw std::invalid_argument(to<string>(
+            "expected an integer value for FileHandlerFactory "
+            "\"max_buffer_size\": ",
+            *maxBufferOption));
+      }
+      if (maxBufferSize == 0) {
+        throw std::invalid_argument(to<string>(
+            "expected a positive value for FileHandlerFactory "
+            "\"max_buffer_size\": ",
+            *maxBufferOption));
+      }
+      asyncWriter->setMaxBufferSize(maxBufferSize);
+    }
+    writer = std::move(asyncWriter);
+  } else {
+    if (maxBufferOption) {
+      throw std::invalid_argument(to<string>(
+          "the \"max_buffer_size\" option is only valid for async file "
+          "handlers"));
+    }
+    writer = make_shared<ImmediateFileWriter>(std::move(outputFile));
+  }
+
+  return make_shared<StandardLogHandler>(formatter, writer);
+}
+
+} // namespace folly
diff --git a/folly/experimental/logging/FileHandlerFactory.h b/folly/experimental/logging/FileHandlerFactory.h
new file mode 100644 (file)
index 0000000..20142be
--- /dev/null
@@ -0,0 +1,38 @@
+/*
+ * Copyright 2004-present Facebook, 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 <folly/experimental/logging/LogHandlerFactory.h>
+
+namespace folly {
+
+/**
+ * FileHandlerFactory is a LogHandlerFactory that constructs log handlers
+ * that write to a file.
+ *
+ * It can construct handlers that use either ImmediateFileWriter or
+ * AsyncFileWriter.
+ */
+class FileHandlerFactory : public LogHandlerFactory {
+ public:
+  StringPiece getType() const override {
+    return "file";
+  }
+
+  std::shared_ptr<LogHandler> createHandler(const Options& options) override;
+};
+
+} // namespace folly
index 42c341b..8678fa3 100644 (file)
@@ -50,6 +50,13 @@ class ImmediateFileWriter : public LogWriter {
   void writeMessage(folly::StringPiece buffer, uint32_t flags = 0) override;
   void flush() override;
 
+  /**
+   * Get the output file.
+   */
+  const folly::File& getFile() const {
+    return file_;
+  }
+
  private:
   ImmediateFileWriter(ImmediateFileWriter const&) = delete;
   ImmediateFileWriter& operator=(ImmediateFileWriter const&) = delete;
diff --git a/folly/experimental/logging/LogHandlerFactory.h b/folly/experimental/logging/LogHandlerFactory.h
new file mode 100644 (file)
index 0000000..f85c5fb
--- /dev/null
@@ -0,0 +1,70 @@
+/*
+ * Copyright 2004-present Facebook, 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 <memory>
+#include <string>
+#include <unordered_map>
+
+#include <folly/CppAttributes.h>
+#include <folly/Range.h>
+
+namespace folly {
+
+class LogHandler;
+
+class LogHandlerFactory {
+ public:
+  using Options = std::unordered_map<std::string, std::string>;
+
+  virtual ~LogHandlerFactory() = default;
+
+  /**
+   * Get the type name of this LogHandlerFactory.
+   *
+   * The type field in the LogHandlerConfig for all LogHandlers created by this
+   * factory should match the type of the LogHandlerFactory.
+   *
+   * The type of a LogHandlerFactory should never change.  The returned
+   * StringPiece should be valid for the lifetime of the LogHandlerFactory.
+   */
+  virtual StringPiece getType() const = 0;
+
+  /**
+   * Create a new LogHandler.
+   */
+  virtual std::shared_ptr<LogHandler> createHandler(const Options& options) = 0;
+
+  /**
+   * Update an existing LogHandler with a new configuration.
+   *
+   * This may create a new LogHandler object, or it may update the existing
+   * LogHandler in place.
+   *
+   * The returned pointer will point to the input handler if it was updated in
+   * place, or will point to a new LogHandler if a new one was created.
+   */
+  virtual std::shared_ptr<LogHandler> updateHandler(
+      FOLLY_MAYBE_UNUSED const std::shared_ptr<LogHandler>& existingHandler,
+      const Options& options) {
+    // Subclasses may override this with functionality to update an existing
+    // handler in-place.  However, provide a default implementation that simply
+    // calls createHandler() to always create a new handler object.
+    return createHandler(options);
+  }
+};
+
+} // namespace folly
index 5612102..61e6408 100644 (file)
@@ -4,6 +4,7 @@ lib_LTLIBRARIES = libfollylogging.la
 
 libfollylogging_la_SOURCES = \
        AsyncFileWriter.cpp \
+       FileHandlerFactory.cpp \
        GlogStyleFormatter.cpp \
        ImmediateFileWriter.cpp \
        Init.cpp \
index 94b2699..3a1e4e4 100644 (file)
@@ -44,6 +44,20 @@ class StandardLogHandler : public LogHandler {
       std::shared_ptr<LogWriter> writer);
   ~StandardLogHandler();
 
+  /**
+   * Get the LogFormatter used by this handler.
+   */
+  const std::shared_ptr<LogFormatter>& getFormatter() const {
+    return formatter_;
+  }
+
+  /**
+   * Get the LogWriter used by this handler.
+   */
+  const std::shared_ptr<LogWriter>& getWriter() const {
+    return writer_;
+  }
+
   /**
    * Get the handler's current LogLevel.
    *
@@ -71,7 +85,14 @@ class StandardLogHandler : public LogHandler {
 
  private:
   std::atomic<LogLevel> level_{LogLevel::NONE};
-  std::shared_ptr<LogFormatter> formatter_;
-  std::shared_ptr<LogWriter> writer_;
+
+  // The formatter_ and writer_ member variables are const, and cannot be
+  // modified after the StandardLogHandler is constructed.  This allows them to
+  // be accessed without locking when handling a message.  To change these
+  // values, create a new StandardLogHandler object and replace the old handler
+  // with the new one in the LoggerDB.
+
+  const std::shared_ptr<LogFormatter> formatter_;
+  const std::shared_ptr<LogWriter> writer_;
 };
 } // namespace folly
diff --git a/folly/experimental/logging/test/FileHandlerFactoryTest.cpp b/folly/experimental/logging/test/FileHandlerFactoryTest.cpp
new file mode 100644 (file)
index 0000000..83724f2
--- /dev/null
@@ -0,0 +1,245 @@
+/*
+ * Copyright 2004-present Facebook, 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.
+ */
+#include <folly/experimental/logging/FileHandlerFactory.h>
+
+#include <folly/Exception.h>
+#include <folly/experimental/TestUtil.h>
+#include <folly/experimental/logging/AsyncFileWriter.h>
+#include <folly/experimental/logging/GlogStyleFormatter.h>
+#include <folly/experimental/logging/ImmediateFileWriter.h>
+#include <folly/experimental/logging/StandardLogHandler.h>
+#include <folly/portability/GTest.h>
+
+using namespace folly;
+using folly::test::TemporaryFile;
+using std::make_pair;
+
+void checkAsyncWriter(
+    const LogWriter* writer,
+    const char* expectedPath,
+    size_t expectedMaxBufferSize) {
+  auto asyncWriter = dynamic_cast<const AsyncFileWriter*>(writer);
+  ASSERT_TRUE(asyncWriter)
+      << "FileHandlerFactory should have created an AsyncFileWriter";
+  EXPECT_EQ(expectedMaxBufferSize, asyncWriter->getMaxBufferSize());
+
+  // Make sure this refers to the expected output file
+  struct stat expectedStatInfo;
+  checkUnixError(stat(expectedPath, &expectedStatInfo), "stat failed");
+  struct stat actualStatInfo;
+  checkUnixError(
+      fstat(asyncWriter->getFile().fd(), &actualStatInfo), "fstat failed");
+  EXPECT_EQ(expectedStatInfo.st_dev, actualStatInfo.st_dev);
+  EXPECT_EQ(expectedStatInfo.st_ino, actualStatInfo.st_ino);
+}
+
+void checkAsyncWriter(
+    const LogWriter* writer,
+    int expectedFD,
+    size_t expectedMaxBufferSize) {
+  auto asyncWriter = dynamic_cast<const AsyncFileWriter*>(writer);
+  ASSERT_TRUE(asyncWriter)
+      << "FileHandlerFactory should have created an AsyncFileWriter";
+  EXPECT_EQ(expectedMaxBufferSize, asyncWriter->getMaxBufferSize());
+  EXPECT_EQ(expectedFD, asyncWriter->getFile().fd());
+}
+
+TEST(FileHandlerFactory, pathOnly) {
+  FileHandlerFactory factory;
+
+  TemporaryFile tmpFile{"logging_test"};
+  auto options = FileHandlerFactory::Options{
+      make_pair("path", tmpFile.path().string()),
+  };
+  auto handler = factory.createHandler(options);
+
+  auto stdHandler = std::dynamic_pointer_cast<StandardLogHandler>(handler);
+  ASSERT_TRUE(stdHandler);
+
+  auto formatter =
+      std::dynamic_pointer_cast<GlogStyleFormatter>(stdHandler->getFormatter());
+  EXPECT_TRUE(formatter)
+      << "FileHandlerFactory should have created a GlogStyleFormatter";
+
+  checkAsyncWriter(
+      stdHandler->getWriter().get(),
+      tmpFile.path().string().c_str(),
+      AsyncFileWriter::kDefaultMaxBufferSize);
+}
+
+TEST(FileHandlerFactory, stderrStream) {
+  FileHandlerFactory factory;
+
+  TemporaryFile tmpFile{"logging_test"};
+  auto options = FileHandlerFactory::Options{
+      make_pair("stream", "stderr"),
+  };
+  auto handler = factory.createHandler(options);
+
+  auto stdHandler = std::dynamic_pointer_cast<StandardLogHandler>(handler);
+  ASSERT_TRUE(stdHandler);
+
+  auto formatter =
+      std::dynamic_pointer_cast<GlogStyleFormatter>(stdHandler->getFormatter());
+  EXPECT_TRUE(formatter)
+      << "FileHandlerFactory should have created a GlogStyleFormatter";
+
+  checkAsyncWriter(
+      stdHandler->getWriter().get(),
+      STDERR_FILENO,
+      AsyncFileWriter::kDefaultMaxBufferSize);
+}
+
+TEST(FileHandlerFactory, stdoutWithMaxBuffer) {
+  FileHandlerFactory factory;
+
+  TemporaryFile tmpFile{"logging_test"};
+  auto options = FileHandlerFactory::Options{
+      make_pair("stream", "stdout"),
+      make_pair("max_buffer_size", "4096"),
+  };
+  auto handler = factory.createHandler(options);
+
+  auto stdHandler = std::dynamic_pointer_cast<StandardLogHandler>(handler);
+  ASSERT_TRUE(stdHandler);
+
+  auto formatter =
+      std::dynamic_pointer_cast<GlogStyleFormatter>(stdHandler->getFormatter());
+  EXPECT_TRUE(formatter)
+      << "FileHandlerFactory should have created a GlogStyleFormatter";
+
+  checkAsyncWriter(stdHandler->getWriter().get(), STDOUT_FILENO, 4096);
+}
+
+TEST(FileHandlerFactory, pathWithMaxBufferSize) {
+  FileHandlerFactory factory;
+
+  TemporaryFile tmpFile{"logging_test"};
+  auto options = FileHandlerFactory::Options{
+      make_pair("path", tmpFile.path().string()),
+      make_pair("max_buffer_size", "4096000"),
+  };
+  auto handler = factory.createHandler(options);
+
+  auto stdHandler = std::dynamic_pointer_cast<StandardLogHandler>(handler);
+  ASSERT_TRUE(stdHandler);
+
+  auto formatter =
+      std::dynamic_pointer_cast<GlogStyleFormatter>(stdHandler->getFormatter());
+  EXPECT_TRUE(formatter)
+      << "FileHandlerFactory should have created a GlogStyleFormatter";
+
+  checkAsyncWriter(
+      stdHandler->getWriter().get(), tmpFile.path().string().c_str(), 4096000);
+}
+
+TEST(FileHandlerFactory, nonAsyncStderr) {
+  FileHandlerFactory factory;
+
+  TemporaryFile tmpFile{"logging_test"};
+  auto options = FileHandlerFactory::Options{
+      make_pair("stream", "stderr"),
+      make_pair("async", "no"),
+  };
+  auto handler = factory.createHandler(options);
+
+  auto stdHandler = std::dynamic_pointer_cast<StandardLogHandler>(handler);
+  ASSERT_TRUE(stdHandler);
+
+  auto formatter =
+      std::dynamic_pointer_cast<GlogStyleFormatter>(stdHandler->getFormatter());
+  EXPECT_TRUE(formatter)
+      << "FileHandlerFactory should have created a GlogStyleFormatter";
+
+  auto writer =
+      std::dynamic_pointer_cast<ImmediateFileWriter>(stdHandler->getWriter());
+  ASSERT_TRUE(writer);
+  EXPECT_EQ(STDERR_FILENO, writer->getFile().fd());
+}
+
+TEST(FileHandlerFactory, errors) {
+  FileHandlerFactory factory;
+  TemporaryFile tmpFile{"logging_test"};
+
+  {
+    auto options = FileHandlerFactory::Options{};
+    EXPECT_THROW(factory.createHandler(options), std::invalid_argument)
+        << "one of path or stream required";
+  }
+
+  {
+    auto options = FileHandlerFactory::Options{
+        make_pair("path", tmpFile.path().string()),
+        make_pair("stream", "stderr"),
+    };
+    EXPECT_THROW(factory.createHandler(options), std::invalid_argument)
+        << "path and stream cannot both be specified";
+  }
+
+  {
+    auto options = FileHandlerFactory::Options{
+        make_pair("stream", "nonstdout"),
+    };
+    EXPECT_THROW(factory.createHandler(options), std::invalid_argument)
+        << "invalid stream";
+  }
+
+  {
+    auto options = FileHandlerFactory::Options{
+        make_pair("stream", "stderr"),
+        make_pair("async", "foobar"),
+    };
+    EXPECT_THROW(factory.createHandler(options), std::invalid_argument)
+        << "invalid async value";
+  }
+
+  {
+    auto options = FileHandlerFactory::Options{
+        make_pair("stream", "stderr"),
+        make_pair("async", "false"),
+        make_pair("max_buffer_size", "1234"),
+    };
+    EXPECT_THROW(factory.createHandler(options), std::invalid_argument)
+        << "max_buffer_size only valid for async writers";
+  }
+
+  {
+    auto options = FileHandlerFactory::Options{
+        make_pair("stream", "stderr"),
+        make_pair("max_buffer_size", "hello"),
+    };
+    EXPECT_THROW(factory.createHandler(options), std::invalid_argument)
+        << "max_buffer_size must be an integer";
+  }
+
+  {
+    auto options = FileHandlerFactory::Options{
+        make_pair("stream", "stderr"),
+        make_pair("max_buffer_size", "0"),
+    };
+    EXPECT_THROW(factory.createHandler(options), std::invalid_argument)
+        << "max_buffer_size must be a positive integer";
+  }
+
+  {
+    auto options = FileHandlerFactory::Options{
+        make_pair("stream", "stderr"),
+        make_pair("foo", "bar"),
+    };
+    EXPECT_THROW(factory.createHandler(options), std::invalid_argument)
+        << "unknown parameter foo";
+  }
+}