get histogram detail (#9)

librocksdb_sys/crocksdb/c.cc

@@ -79,6 +79,7 @@ using rocksdb::RestoreOptions;
 using rocksdb::CompactRangeOptions;
 using rocksdb::RateLimiter;
 using rocksdb::NewGenericRateLimiter;
+using rocksdb::HistogramData;
 
 using std::shared_ptr;
 
@@ -116,6 +117,7 @@ struct crocksdb_envoptions_t      { EnvOptions        rep; };
 struct crocksdb_ingestexternalfileoptions_t  { IngestExternalFileOptions rep; };
 struct crocksdb_sstfilewriter_t   { SstFileWriter*    rep; };
 struct crocksdb_ratelimiter_t     { RateLimiter*      rep; };
+struct crocksdb_histogramdata_t   { HistogramData     rep; };
 
 struct crocksdb_compactionfiltercontext_t {
   CompactionFilter::Context rep;
@@ -2032,6 +2034,28 @@ char* crocksdb_options_statistics_get_histogram_string(crocksdb_options_t* opt,
   return nullptr;
 }
 
+unsigned char crocksdb_options_statistics_get_histogram(
+    crocksdb_options_t* opt,
+    uint32_t type,
+    double* median,
+    double* percentile95,
+    double* percentile99,
+    double* average,
+    double* standard_deviation) {
+  rocksdb::Statistics* statistics = opt->rep.statistics.get();
+  if (statistics) {
+    crocksdb_histogramdata_t data;
+    statistics->histogramData(type, &data.rep);
+    *median = data.rep.median;
+    *percentile95 = data.rep.percentile95;
+    *percentile99 = data.rep.percentile99;
+    *average = data.rep.average;
+    *standard_deviation = data.rep.standard_deviation;
+    return 1;
+  }
+  return 0;
+}
+
 void crocksdb_options_set_ratelimiter(crocksdb_options_t *opt, crocksdb_ratelimiter_t *limiter) {
   opt->rep.rate_limiter.reset(limiter->rep);
   limiter->rep = nullptr;

librocksdb_sys/crocksdb/rocksdb/c.h

@@ -624,6 +624,14 @@ extern C_ROCKSDB_LIBRARY_API uint64_t crocksdb_options_statistics_get_and_reset_
 extern C_ROCKSDB_LIBRARY_API char*
 crocksdb_options_statistics_get_histogram_string(crocksdb_options_t* opt,
                                                  uint32_t type);
+extern C_ROCKSDB_LIBRARY_API unsigned char crocksdb_options_statistics_get_histogram(
+    crocksdb_options_t* opt,
+    uint32_t type,
+    double* median,
+    double* percentile95,
+    double* percentile99,
+    double* average,
+    double* standard_deviation);
 
 extern C_ROCKSDB_LIBRARY_API void crocksdb_options_set_max_write_buffer_number(
     crocksdb_options_t*, int);

librocksdb_sys/src/lib.rs

@@ -249,6 +249,13 @@ extern "C" {
     pub fn crocksdb_options_statistics_get_histogram_string(options: *mut DBOptions,
                                                             hist_type: DBStatisticsHistogramType)
                                                             -> *const c_char;
+    pub fn crocksdb_options_statistics_get_histogram(options: *mut DBOptions,
+                                                     hist_type: DBStatisticsHistogramType,
+                                                     median: *mut c_double,
+                                                     percentile95: *mut c_double,
+                                                     percentile99: *mut c_double,
+                                                     average: *mut c_double,
+                                                     standard_deviation: *mut c_double) -> bool;
     pub fn crocksdb_options_set_stats_dump_period_sec(options: *mut DBOptions, v: usize);
     pub fn crocksdb_options_set_num_levels(options: *mut DBOptions, v: c_int);
     pub fn crocksdb_options_set_db_log_dir(options: *mut DBOptions, path: *const c_char);

src/lib.rs

@@ -37,5 +37,5 @@ pub use merge_operator::MergeOperands;
 pub use rocksdb::{DB, DBIterator, DBVector, Kv, SeekKey, Writable, WriteBatch, CFHandle, Range,
                   BackupEngine};
 pub use rocksdb_options::{BlockBasedOptions, Options, ReadOptions, WriteOptions, RestoreOptions,
-                          IngestExternalFileOptions, EnvOptions};
+                          IngestExternalFileOptions, EnvOptions, HistogramData};
 pub use slice_transform::SliceTransform;

src/rocksdb.rs

@@ -17,7 +17,7 @@ use crocksdb_ffi::{self, DBWriteBatch, DBCFHandle, DBInstance, DBBackupEngine,
                    DBStatisticsTickerType, DBStatisticsHistogramType};
 use libc::{self, c_int, c_void, size_t};
 use rocksdb_options::{Options, ReadOptions, UnsafeSnap, WriteOptions, FlushOptions,
-                      RestoreOptions, IngestExternalFileOptions};
+                      RestoreOptions, IngestExternalFileOptions, HistogramData};
 use std::{fs, ptr, slice};
 use std::collections::BTreeMap;
 use std::collections::btree_map::Entry;
@@ -874,6 +874,12 @@ impl DB {
         self.opts.get_statistics_histogram_string(hist_type)
     }
 
+    pub fn get_statistics_histogram(&self,
+                                    hist_type: DBStatisticsHistogramType)
+                                    -> Option<HistogramData> {
+        self.opts.get_statistics_histogram(hist_type)
+    }
+
     pub fn get_options(&self) -> &Options {
         &self.opts
     }

src/rocksdb_options.rs

@@ -26,6 +26,15 @@ use slice_transform::{SliceTransform, new_slice_transform};
 use std::ffi::{CStr, CString};
 use std::mem;
 
+#[derive(Default, Debug)]
+pub struct HistogramData {
+    pub median: f64,
+    pub percentile95: f64,
+    pub percentile99: f64,
+    pub average: f64,
+    pub standard_deviation: f64,
+}
+
 pub struct BlockBasedOptions {
     inner: *mut DBBlockBasedTableOptions,
 }
@@ -540,6 +549,25 @@ impl Options {
         }
     }
 
+    pub fn get_statistics_histogram(&self,
+                                    hist_type: DBStatisticsHistogramType)
+                                    -> Option<HistogramData> {
+        unsafe {
+            let mut data = HistogramData::default();
+            let ret = crocksdb_ffi::crocksdb_options_statistics_get_histogram(self.inner,
+                                                hist_type,
+                                                &mut data.median,
+                                                &mut data.percentile95,
+                                                &mut data.percentile99,
+                                                &mut data.average,
+                                                &mut data.standard_deviation);
+            if !ret {
+                return None;
+            }
+            Some(data)
+        }
+    }
+
     pub fn get_statistics_histogram_string(&self,
                                            hist_type: DBStatisticsHistogramType)
                                            -> Option<String> {

test/test_statistics.rs

@@ -37,4 +37,5 @@ fn test_db_statistics() {
     assert!(db.get_and_reset_statistics_ticker_count(TickerType::BlockCacheHit) > 0);
     assert_eq!(db.get_statistics_ticker_count(TickerType::BlockCacheHit), 0);
     assert!(db.get_statistics_histogram_string(HistogramType::DbGetMicros).is_some());
+    assert!(db.get_statistics_histogram(HistogramType::DbGetMicros).is_some());
 }