Add counters to count gets and writes

Summary: Add Tickers to count Write's and Get's

Test Plan: make check

Reviewers: dhruba, chip

Reviewed By: dhruba

CC: leveldb

Differential Revision: https://reviews.facebook.net/D7977

db/db_impl.cc

@@ -1875,6 +1875,7 @@ Status DBImpl::Get(const ReadOptions& options,
   mem->Unref();
   imm.UnrefAll();
   current->Unref();
+  RecordTick(options_.statistics, NUMBER_KEYS_READ);
   return s;
 }
 
@@ -1930,7 +1931,10 @@ Status DBImpl::Write(const WriteOptions& options, WriteBatch* my_batch) {
   if (status.ok() && my_batch != NULL) {  // NULL batch is for compactions
     WriteBatch* updates = BuildBatchGroup(&last_writer);
     WriteBatchInternal::SetSequence(updates, last_sequence + 1);
-    last_sequence += WriteBatchInternal::Count(updates);
+    int my_batch_count = WriteBatchInternal::Count(updates);
+    last_sequence += my_batch_count;
+    // Record statistics
+    RecordTick(options_.statistics, NUMBER_KEYS_WRITTEN, my_batch_count);
 
     // Add to log and apply to memtable.  We can release the lock
     // during this phase since &w is currently responsible for logging
@@ -1977,7 +1981,6 @@ Status DBImpl::Write(const WriteOptions& options, WriteBatch* my_batch) {
   if (!writers_.empty()) {
     writers_.front()->cv.Signal();
   }
-
   return status;
 }
 

db/db_statistics.h

@@ -35,9 +35,9 @@ class DBStatistics: public Statistics {
     return allTickers_[tickerType].getCount();
   }
 
-  void recordTick(Tickers tickerType) {
+  void recordTick(Tickers tickerType, uint64_t count) {
     assert(tickerType < TICKER_ENUM_MAX);
-    allTickers_[tickerType].recordTick();
+    allTickers_[tickerType].recordTick(count);
   }
 
  private:

include/leveldb/options.h

@@ -252,6 +252,8 @@ struct Options {
   int max_grandparent_overlap_factor;
 
   // If non-null, then we should collect metrics about database operations
+  // Statistics objects should not be shared between DB instances as
+  // it does not use any locks to prevent concurrent updates.
   Statistics* statistics;
 
   // If true, then the contents of data files are not synced

include/leveldb/statistics.h

@@ -24,7 +24,11 @@ enum Tickers {
   COMPACTION_KEY_DROP_NEWER_ENTRY = 3, // key was written with a newer value.
   COMPACTION_KEY_DROP_OBSOLETE = 4, // The key is obsolete.
   COMPACTION_KEY_DROP_USER = 5, // user compaction function has dropped the key.
-  TICKER_ENUM_MAX = 6,
+  // Number of keys written to the database via the Put and Write call's
+  NUMBER_KEYS_WRITTEN = 6,
+  // Number of Keys read,
+  NUMBER_KEYS_READ = 7,
+  TICKER_ENUM_MAX = 8,
 };
 
 
@@ -40,6 +44,9 @@ class Ticker {
     count_++;
   }
 
+  inline void recordTick(int count) {
+    count_ += count;
+  }
   inline uint64_t getCount() {
     return count_;
   }
@@ -66,7 +73,7 @@ class Statistics {
   virtual ~Statistics() {}
 
   virtual long getTickerCount(Tickers tickerType) = 0;
-  virtual void recordTick(Tickers tickerType) = 0;
+  virtual void recordTick(Tickers tickerType, uint64_t count = 0) = 0;
 
  protected:
   long numFileOpens_;
@@ -75,11 +82,13 @@ class Statistics {
 };
 
 // Ease of Use functions
-inline void RecordTick(Statistics* const statistics, Tickers ticker) {
+inline void RecordTick(Statistics* const statistics,
+                       Tickers ticker,
+                       uint64_t count = 1) {
   if (statistics != NULL) {
-    statistics->recordTick(ticker);
+    statistics->recordTick(ticker, count);
   }
-};
+}
 }  // namespace leveldb
 
 #endif  // STORAGE_LEVELDB_INCLUDE_STATISTICS_H_