Merge pull request #197 from aleksuss/immutable-op-cf

Methods `create_cf` and `drop_cf` are immutable.

src/db.rs

@@ -19,8 +19,7 @@ use {ColumnFamily, ColumnFamilyDescriptor, Error, Options, WriteOptions, DB};
 
 use libc::{self, c_char, c_int, c_uchar, c_void, size_t};
 use std::collections::BTreeMap;
-use std::ffi::CStr;
-use std::ffi::CString;
+use std::ffi::{CStr, CString};
 use std::fmt;
 use std::fs;
 use std::ops::Deref;
@@ -28,6 +27,7 @@ use std::path::Path;
 use std::ptr;
 use std::slice;
 use std::str;
+use std::sync::{Arc, RwLock};
 
 pub fn new_bloom_filter(bits: c_int) -> *mut ffi::rocksdb_filterpolicy_t {
     unsafe { ffi::rocksdb_filterpolicy_create_bloom(bits) }
@@ -386,7 +386,7 @@ impl DBRawIterator {
     /// if the iterator's seek position is ever moved by any of the seek commands or the
     /// ``.next()`` and ``.previous()`` methods as the underlying buffer may be reused
     /// for something else or freed entirely.
-    pub unsafe fn key_inner<'a>(&'a self) -> Option<&'a [u8]> {
+    pub unsafe fn key_inner(&self) -> Option<&[u8]> {
         if self.valid() {
             let mut key_len: size_t = 0;
             let key_len_ptr: *mut size_t = &mut key_len;
@@ -410,7 +410,7 @@ impl DBRawIterator {
     /// if the iterator's seek position is ever moved by any of the seek commands or the
     /// ``.next()`` and ``.previous()`` methods as the underlying buffer may be reused
     /// for something else or freed entirely.
-    pub unsafe fn value_inner<'a>(&'a self) -> Option<&'a [u8]> {
+    pub unsafe fn value_inner(&self) -> Option<&[u8]> {
         if self.valid() {
             let mut val_len: size_t = 0;
             let val_len_ptr: *mut size_t = &mut val_len;
@@ -454,7 +454,7 @@ impl DBIterator {
         mode: IteratorMode,
     ) -> Result<DBIterator, Error> {
         let mut rv = DBIterator {
-            raw: try!(DBRawIterator::new_cf(db, cf_handle, readopts)),
+            raw: DBRawIterator::new_cf(db, cf_handle, readopts)?,
             direction: Direction::Forward, // blown away by set_mode()
             just_seeked: false,
         };
@@ -647,7 +647,7 @@ impl DB {
         }
 
         let db: *mut ffi::rocksdb_t;
-        let mut cf_map = BTreeMap::new();
+        let cf_map = Arc::new(RwLock::new(BTreeMap::new()));
 
         if cfs.len() == 0 {
             unsafe {
@@ -701,7 +701,9 @@ impl DB {
             }
 
             for (n, h) in cfs_v.iter().zip(cfhandles) {
-                cf_map.insert(n.name.clone(), ColumnFamily { inner: h });
+                cf_map.write()
+                    .map_err(|e| Error::new(e.to_string()))?
+                    .insert(n.name.clone(), ColumnFamily { inner: h });
             }
         }
 
@@ -856,7 +858,7 @@ impl DB {
         self.get_cf_opt(cf, key, &ReadOptions::default())
     }
 
-    pub fn create_cf(&mut self, name: &str, opts: &Options) -> Result<ColumnFamily, Error> {
+    pub fn create_cf(&self, name: &str, opts: &Options) -> Result<ColumnFamily, Error> {
         let cname = match CString::new(name.as_bytes()) {
             Ok(c) => c,
             Err(_) => {
@@ -874,31 +876,30 @@ impl DB {
                 cname.as_ptr(),
             ));
             let cf = ColumnFamily { inner: cf_handler };
-            self.cfs.insert(name.to_string(), cf);
+            self.cfs.write().map_err(|e| Error::new(e.to_string()))?
+                .insert(name.to_string(), cf);
             cf
         };
         Ok(cf)
     }
 
-    pub fn drop_cf(&mut self, name: &str) -> Result<(), Error> {
-        let cf = self.cfs.get(name);
-        if cf.is_none() {
-            return Err(Error::new(
-                format!("Invalid column family: {}", name).to_owned(),
-            ));
-        }
-        unsafe {
-            ffi_try!(ffi::rocksdb_drop_column_family(
-                self.inner,
-                cf.unwrap().inner,
-            ));
+    pub fn drop_cf(&self, name: &str) -> Result<(), Error> {
+        if let Some(cf) = self.cfs.write().map_err(|e| Error::new(e.to_string()))?
+            .remove(name) {
+            unsafe {
+                ffi_try!(ffi::rocksdb_drop_column_family(self.inner, cf.inner,));
+            }
+            Ok(())
+        } else {
+            Err(Error::new(
+                format!("Invalid column family: {}", name).to_owned()
+            ))
         }
-        Ok(())
     }
 
     /// Return the underlying column family handle.
     pub fn cf_handle(&self, name: &str) -> Option<ColumnFamily> {
-        self.cfs.get(name).cloned()
+        self.cfs.read().ok()?.get(name).cloned()
     }
 
     pub fn iterator(&self, mode: IteratorMode) -> DBIterator {
@@ -915,7 +916,7 @@ impl DB {
         DBIterator::new(self, &opts, mode)
     }
 
-    pub fn prefix_iterator<'a>(&self, prefix: &'a [u8]) -> DBIterator {
+    pub fn prefix_iterator(&self, prefix: &[u8]) -> DBIterator {
         let mut opts = ReadOptions::default();
         opts.set_prefix_same_as_start(true);
         DBIterator::new(self, &opts, IteratorMode::From(prefix, Direction::Forward))
@@ -940,10 +941,10 @@ impl DB {
         DBIterator::new_cf(self, cf_handle, &opts, mode)
     }
 
-    pub fn prefix_iterator_cf<'a>(
+    pub fn prefix_iterator_cf(
         &self,
         cf_handle: ColumnFamily,
-        prefix: &'a [u8],
+        prefix: &[u8]
     ) -> Result<DBIterator, Error> {
         let mut opts = ReadOptions::default();
         opts.set_prefix_same_as_start(true);
@@ -1241,8 +1242,10 @@ impl Drop for WriteBatch {
 impl Drop for DB {
     fn drop(&mut self) {
         unsafe {
-            for cf in self.cfs.values() {
-                ffi::rocksdb_column_family_handle_destroy(cf.inner);
+            if let Ok(cfs) = self.cfs.read() {
+                for cf in cfs.values() {
+                    ffi::rocksdb_column_family_handle_destroy(cf.inner);
+                }
             }
             ffi::rocksdb_close(self.inner);
         }

src/lib.rs

@@ -74,13 +74,14 @@ use std::collections::BTreeMap;
 use std::error;
 use std::fmt;
 use std::path::PathBuf;
+use std::sync::{Arc, RwLock};
 
 /// A RocksDB database.
 ///
 /// See crate level documentation for a simple usage example.
 pub struct DB {
     inner: *mut ffi::rocksdb_t,
-    cfs: BTreeMap<String, ColumnFamily>,
+    cfs: Arc<RwLock<BTreeMap<String, ColumnFamily>>>,
     path: PathBuf,
 }
 
@@ -101,7 +102,7 @@ pub struct Error {
 
 impl Error {
     fn new(message: String) -> Error {
-        Error { message: message }
+        Error { message }
     }
 
     pub fn to_string(self) -> String {

tests/test_column_family.rs

@@ -27,7 +27,7 @@ pub fn test_column_family() {
         let mut opts = Options::default();
         opts.create_if_missing(true);
         opts.set_merge_operator("test operator", test_provided_merge, None);
-        let mut db = DB::open(&opts, &n).unwrap();
+        let db = DB::open(&opts, &n).unwrap();
         let opts = Options::default();
         match db.create_cf("cf1", &opts) {
             Ok(_db) => println!("cf1 created successfully"),
@@ -80,7 +80,7 @@ pub fn test_column_family() {
     {}
     // should b able to drop a cf
     {
-        let mut db = DB::open_cf(&Options::default(), &n, &["cf1"]).unwrap();
+        let db = DB::open_cf(&Options::default(), &n, &["cf1"]).unwrap();
         match db.drop_cf("cf1") {
             Ok(_) => println!("cf1 successfully dropped."),
             Err(e) => panic!("failed to drop column family: {}", e),