Add blob index encoder (#272)

librocksdb_sys/crocksdb/c.cc

@@ -4988,6 +4988,18 @@ void ctitandb_decode_blob_index(const char* value, size_t value_size,
   index->blob_size = bi.blob_handle.size;
 }
 
+void ctitandb_encode_blob_index(const ctitandb_blob_index_t& index,
+                                char** value, size_t* value_size) {
+  BlobIndex bi;
+  bi.file_number = index.file_number;
+  bi.blob_handle.offset = index.blob_offset;
+  bi.blob_handle.size = index.blob_size;
+  std::string result;
+  bi.EncodeTo(&result);
+  *value = CopyString(result);
+  *value_size = result.size();
+}
+
 void ctitandb_options_set_disable_background_gc(ctitandb_options_t* options,
                                                 unsigned char disable) {
   options->rep.disable_background_gc = disable;

librocksdb_sys/crocksdb/crocksdb/c.h

@@ -1986,6 +1986,9 @@ extern C_ROCKSDB_LIBRARY_API void ctitandb_decode_blob_index(
     const char* value, size_t value_size, ctitandb_blob_index_t* index,
     char** errptr);
 
+extern C_ROCKSDB_LIBRARY_API void ctitandb_encode_blob_index(
+    const ctitandb_blob_index_t& index, char** value, size_t* value_size);
+
 extern C_ROCKSDB_LIBRARY_API void ctitandb_options_set_disable_background_gc(
     ctitandb_options_t* options, unsigned char disable);
 

rocksdb @ c96bfa2e

-Subproject commit da05929b46cf5e5129b75c1b95feb6d0c41da27c
+Subproject commit c96bfa2e2e75f8fddbfa9362ba072d07b453df20

librocksdb_sys/src/lib.rs

@@ -1822,6 +1822,11 @@ extern "C" {
         index: *mut DBTitanBlobIndex,
         errptr: *mut *mut c_char,
     );
+    pub fn ctitandb_encode_blob_index(
+        index: &DBTitanBlobIndex,
+        value: *mut *mut u8,
+        value_size: *mut u64,
+    );
 
     pub fn ctitandb_options_set_disable_background_gc(opts: *mut DBTitanDBOptions, disable: bool);
     pub fn ctitandb_options_set_max_background_gc(opts: *mut DBTitanDBOptions, size: i32);

src/titan.rs

@@ -2,9 +2,14 @@ use std::ffi::{CStr, CString};
 use std::ops::Deref;
 
 use crocksdb_ffi::{self, DBCompressionType, DBTitanBlobIndex, DBTitanDBOptions};
+use librocksdb_sys::ctitandb_encode_blob_index;
+use std::ffi::c_void;
+use std::ops::DerefMut;
 use std::os::raw::c_double;
 use std::os::raw::c_int;
 use std::os::raw::c_uchar;
+use std::ptr;
+use std::slice;
 
 pub struct TitanDBOptions {
     pub inner: *mut DBTitanDBOptions,
@@ -124,7 +129,7 @@ pub struct TitanBlobIndex {
 }
 
 impl TitanBlobIndex {
-    pub fn decode_from(value: &[u8]) -> Result<Self, String> {
+    pub fn decode(value: &[u8]) -> Result<Self, String> {
         let mut index = Self::default();
         unsafe {
             ffi_try!(ctitandb_decode_blob_index(
@@ -135,6 +140,18 @@ impl TitanBlobIndex {
         }
         Ok(index)
     }
+
+    pub fn encode(&self) -> Vec<u8> {
+        let mut value = ptr::null_mut();
+        let mut value_size: u64 = 0;
+        unsafe {
+            ctitandb_encode_blob_index(&self.inner, &mut value, &mut value_size);
+            let slice = slice::from_raw_parts(value, value_size as usize);
+            let vec = slice.to_vec();
+            libc::free(value as *mut c_void);
+            vec
+        }
+    }
 }
 
 impl Deref for TitanBlobIndex {
@@ -143,3 +160,9 @@ impl Deref for TitanBlobIndex {
         &self.inner
     }
 }
+
+impl DerefMut for TitanBlobIndex {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.inner
+    }
+}

tests/cases/test_titan.rs

@@ -16,6 +16,7 @@ use std::collections::HashMap;
 use byteorder::{LittleEndian, ReadBytesExt, WriteBytesExt};
 use tempdir::TempDir;
 
+use rand::Rng;
 use rocksdb::{
     ColumnFamilyOptions, DBCompressionType, DBEntryType, DBOptions, SeekKey,
     TablePropertiesCollector, TablePropertiesCollectorFactory, TitanBlobIndex, TitanDBOptions,
@@ -64,7 +65,7 @@ impl TablePropertiesCollector for TitanCollector {
         self.num_entries += 1;
         if let DBEntryType::BlobIndex = entry_type {
             self.num_blobs += 1;
-            let index = TitanBlobIndex::decode_from(value).unwrap();
+            let index = TitanBlobIndex::decode(value).unwrap();
             assert!(index.file_number > 0);
             assert!(index.blob_size > 0);
         }
@@ -150,3 +151,17 @@ fn test_titandb() {
     let num_entries = n as u32 * max_value_size as u32;
     check_table_properties(&db, num_entries / 2, num_entries);
 }
+
+#[test]
+fn test_titan_blob_index() {
+    let mut index = TitanBlobIndex::default();
+    let mut rng = rand::thread_rng();
+    index.file_number = rng.gen();
+    index.blob_size = rng.gen();
+    index.blob_offset = rng.gen();
+    let value = index.encode();
+    let index2 = TitanBlobIndex::decode(&value).unwrap();
+    assert_eq!(index2.file_number, index.file_number);
+    assert_eq!(index2.blob_size, index.blob_size);
+    assert_eq!(index2.blob_offset, index.blob_offset);
+}