update README for latest rocksdb version

README.md

@@ -3,7 +3,7 @@ rust-rocksdb
 [![Build Status](https://travis-ci.org/spacejam/rust-rocksdb.svg?branch=master)](https://travis-ci.org/spacejam/rust-rocksdb)
 [![crates.io](http://meritbadge.herokuapp.com/rocksdb)](https://crates.io/crates/rocksdb)
 
-This library has been tested against RocksDB 3.8.1 on linux and OSX.  The 0.1.1 crate should work with the Rust 1.2 stable and nightly releases as of 9/7/15.
+This library has been tested against RocksDB 3.13.1 on linux and OSX.  The 0.1.1 crate should work with the Rust 1.2 stable and nightly releases as of 9/7/15.
 
 ### status
   - [x] basic open/put/get/delete/close
@@ -22,6 +22,9 @@ This library has been tested against RocksDB 3.8.1 on linux and OSX.  The 0.1.1
 Feedback and pull requests welcome!  If a particular feature of RocksDB is important to you, please let me know by opening an issue, and I'll prioritize it.
 
 ###### Prerequisite: RocksDB
+
+First, use your system's package manager to install snappy.  This is optional, but lets rocksdb take advantage of better compression, and some code may require it.
+
 ```bash
 wget https://github.com/facebook/rocksdb/archive/rocksdb-3.8.tar.gz
 tar xvf rocksdb-3.8.tar.gz && cd rocksdb-rocksdb-3.8 && make shared_lib

src/ffi.rs

@@ -15,7 +15,8 @@
 */
 extern crate libc;
 use self::libc::{c_char, c_int, c_void, size_t};
-use std::ffi::CString;
+use std::ffi::{CString, CStr};
+use std::str::from_utf8;
 
 #[derive(Copy, Clone)]
 #[repr(C)]
@@ -92,6 +93,15 @@ pub enum DBUniversalCompactionStyle {
     rocksdb_total_size_compaction_stop_style = 1,
 }
 
+pub fn error_message(ptr: *const i8) -> String {
+    let c_str = unsafe { CStr::from_ptr(ptr) };
+    let s = from_utf8(c_str.to_bytes()).unwrap().to_owned();
+    unsafe{
+        libc::free(ptr as *mut libc::c_void);
+    }
+    s
+}
+
 //TODO audit the use of boolean arguments, b/c I think they need to be u8 instead...
 #[link(name = "rocksdb")]
 extern {
@@ -410,6 +420,9 @@ fn internal() {
         let mut err: *const i8 = 0 as *const i8;
         let err_ptr: *mut *const i8 = &mut err;
         let db = rocksdb_open(opts, cpath_ptr, err_ptr);
+        if !err.is_null() {
+            println!("failed to open rocksdb: {}", error_message(err));
+        }
         assert!(err.is_null());
 
         let writeopts = rocksdb_writeoptions_create();

src/rocksdb.rs

@@ -27,7 +27,7 @@ use std::str::from_utf8;
 
 use self::libc::{c_void, size_t};
 
-use rocksdb_ffi::{self, DBCFHandle};
+use rocksdb_ffi::{self, DBCFHandle, error_message};
 use rocksdb_options::Options;
 
 pub struct DB {
@@ -187,15 +187,6 @@ pub trait Writable {
     fn delete_cf(&self, cf: DBCFHandle, key: &[u8]) -> Result<(), String>;
 }
 
-fn error_message(ptr: *const i8) -> String {
-    let c_str = unsafe { CStr::from_ptr(ptr) };
-    let s = from_utf8(c_str.to_bytes()).unwrap().to_owned();
-    unsafe{
-        libc::free(ptr as *mut libc::c_void);
-    }
-    s
-}
-
 impl DB {
     pub fn open_default(path: &str) -> Result<DB, String> {
         let mut opts = Options::new();