Enlarge log size cap when printing file summary

Summary:
Now the file summary is too small for printing. Enlarge it.
To enable it, allow to pass a size to log buffer.

Test Plan:
Add a unit test.
make all check

Reviewers: ljin, yhchiang

Reviewed By: yhchiang

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D21723

Author: siying

db/compaction_picker.cc

@@ -575,7 +575,7 @@ Compaction* UniversalCompactionPicker::PickCompaction(Version* version,
     return nullptr;
   }
   Version::FileSummaryStorage tmp;
-  LogToBuffer(log_buffer, "[%s] Universal: candidate files(%zu): %s\n",
+  LogToBuffer(log_buffer, 3072, "[%s] Universal: candidate files(%zu): %s\n",
               version->cfd_->GetName().c_str(), version->files_[level].size(),
               version->LevelFileSummary(&tmp, 0));
 

db/version_set.h

@@ -183,10 +183,10 @@ class Version {
   // Return a human-readable short (single-line) summary of the number
   // of files per level.  Uses *scratch as backing store.
   struct LevelSummaryStorage {
-    char buffer[100];
+    char buffer[1000];
   };
   struct FileSummaryStorage {
-    char buffer[1000];
+    char buffer[3000];
   };
   const char* LevelSummary(LevelSummaryStorage* scratch) const;
   // Return a human-readable short (single-line) summary of files

util/env_test.cc

@@ -768,6 +768,41 @@ TEST(EnvPosixTest, LogBufferTest) {
   ASSERT_EQ(10, test_logger.char_x_count);
 }
 
+class TestLogger2 : public Logger {
+ public:
+  explicit TestLogger2(size_t max_log_size) : max_log_size_(max_log_size) {}
+  virtual void Logv(const char* format, va_list ap) override {
+    char new_format[2000];
+    std::fill_n(new_format, sizeof(new_format), '2');
+    {
+      va_list backup_ap;
+      va_copy(backup_ap, ap);
+      int n = vsnprintf(new_format, sizeof(new_format) - 1, format, backup_ap);
+      // 48 bytes for extra information + bytes allocated
+      ASSERT_TRUE(
+          n <= 48 + static_cast<int>(max_log_size_ - sizeof(struct timeval)));
+      ASSERT_TRUE(n > static_cast<int>(max_log_size_ - sizeof(struct timeval)));
+      va_end(backup_ap);
+    }
+  }
+  size_t max_log_size_;
+};
+
+TEST(EnvPosixTest, LogBufferMaxSizeTest) {
+  char bytes9000[9000];
+  std::fill_n(bytes9000, sizeof(bytes9000), '1');
+  bytes9000[sizeof(bytes9000) - 1] = '\0';
+
+  for (size_t max_log_size = 256; max_log_size <= 1024;
+       max_log_size += 1024 - 256) {
+    TestLogger2 test_logger(max_log_size);
+    test_logger.SetInfoLogLevel(InfoLogLevel::INFO_LEVEL);
+    LogBuffer log_buffer(InfoLogLevel::INFO_LEVEL, &test_logger);
+    LogToBuffer(&log_buffer, max_log_size, "%s", bytes9000);
+    log_buffer.FlushBufferToLog();
+  }
+}
+
 }  // namespace rocksdb
 
 int main(int argc, char** argv) {

util/log_buffer.cc

@@ -13,17 +13,17 @@ LogBuffer::LogBuffer(const InfoLogLevel log_level,
                      Logger*info_log)
     : log_level_(log_level), info_log_(info_log) {}
 
-void LogBuffer::AddLogToBuffer(const char* format, va_list ap) {
+void LogBuffer::AddLogToBuffer(size_t max_log_size, const char* format,
+                               va_list ap) {
   if (!info_log_ || log_level_ < info_log_->GetInfoLogLevel()) {
     // Skip the level because of its level.
     return;
   }
 
-  const size_t kLogSizeLimit = 512;
-  char* alloc_mem = arena_.AllocateAligned(kLogSizeLimit);
+  char* alloc_mem = arena_.AllocateAligned(max_log_size);
   BufferedLog* buffered_log = new (alloc_mem) BufferedLog();
   char* p = buffered_log->message;
-  char* limit = alloc_mem + kLogSizeLimit - 1;
+  char* limit = alloc_mem + max_log_size - 1;
 
   // store the time
   gettimeofday(&(buffered_log->now_tv), nullptr);
@@ -61,11 +61,22 @@ void LogBuffer::FlushBufferToLog() {
   logs_.clear();
 }
 
+void LogToBuffer(LogBuffer* log_buffer, size_t max_log_size, const char* format,
+                 ...) {
+  if (log_buffer != nullptr) {
+    va_list ap;
+    va_start(ap, format);
+    log_buffer->AddLogToBuffer(max_log_size, format, ap);
+    va_end(ap);
+  }
+}
+
 void LogToBuffer(LogBuffer* log_buffer, const char* format, ...) {
+  const size_t kDefaultMaxLogSize = 512;
   if (log_buffer != nullptr) {
     va_list ap;
     va_start(ap, format);
-    log_buffer->AddLogToBuffer(format, ap);
+    log_buffer->AddLogToBuffer(kDefaultMaxLogSize, format, ap);
     va_end(ap);
   }
 }

util/log_buffer.h

@@ -21,8 +21,9 @@ class LogBuffer {
   // info_log:  logger to write the logs to
   LogBuffer(const InfoLogLevel log_level, Logger* info_log);
 
-  // Add a log entry to the buffer.
-  void AddLogToBuffer(const char* format, va_list ap);
+  // Add a log entry to the buffer. Use default max_log_size.
+  // max_log_size indicates maximize log size, including some metadata.
+  void AddLogToBuffer(size_t max_log_size, const char* format, va_list ap);
 
   size_t IsEmpty() const { return logs_.empty(); }
 
@@ -44,6 +45,10 @@ class LogBuffer {
 
 // Add log to the LogBuffer for a delayed info logging. It can be used when
 // we want to add some logs inside a mutex.
+// max_log_size indicates maximize log size, including some metadata.
+extern void LogToBuffer(LogBuffer* log_buffer, size_t max_log_size,
+                        const char* format, ...);
+// Same as previous function, but with default max log size.
 extern void LogToBuffer(LogBuffer* log_buffer, const char* format, ...);
 
 }  // namespace rocksdb