add methods.

is_readonly?
is_open?

ext/rocksdb/rocksdb_db_rb.cc

@@ -50,7 +50,7 @@ extern "C" {
     rocksdb_pointer* db_pointer;
     Data_Get_Struct(self, rocksdb_pointer, db_pointer);
     db_pointer->db = NULL;
-
+    db_pointer->readonly = true;
     Data_Get_Struct(self, rocksdb_pointer, db_pointer);
 
     return Qtrue;
@@ -317,7 +317,23 @@ extern "C" {
   VALUE rocksdb_db_debug(VALUE self){
     return Qnil;
   }
-
+  VALUE rocksdb_db_is_readonly(VALUE self){
+    rocksdb_pointer* db_pointer;
+    Data_Get_Struct(self, rocksdb_pointer, db_pointer);
+    if (db_pointer->readonly) {
+      return Qtrue;
+    }
+    if (!db_pointer->readonly) {
+      return Qfalse;
+    }
+    return Qnil;
+  }
+  VALUE rocksdb_db_is_open(VALUE self){
+    rocksdb_pointer* db_pointer;
+    Data_Get_Struct(self, rocksdb_pointer, db_pointer);
+    return (db_pointer->db == NULL) ? Qfalse : Qtrue;
+  }
+
   VALUE rocksdb_db_compact(int argc, VALUE* argv, VALUE self) {
     VALUE v_from, v_to;
     rocksdb::Slice from, to;

ext/rocksdb/rocksdb_db_rb.h

@@ -14,6 +14,8 @@ extern "C" {
   VALUE rocksdb_db_exists(VALUE self, VALUE v_key);
   VALUE rocksdb_db_close(VALUE self);
   VALUE rocksdb_db_debug(VALUE self);
+  VALUE rocksdb_db_is_readonly(VALUE self);
+  VALUE rocksdb_db_is_open(VALUE self);
   VALUE rocksdb_db_new_iterator(VALUE self);
   VALUE rocksdb_db_each(VALUE self);
   VALUE rocksdb_db_each_index(VALUE self);

ext/rocksdb/rocksdb_rb.cc

@@ -32,6 +32,8 @@ extern "C" {
     rb_define_method(cRocksdb_db, "debug", (METHOD)rocksdb_db_debug, 0);
     rb_define_method(cRocksdb_db, "new_iterator", (METHOD)rocksdb_db_new_iterator, 0);
     rb_define_method(cRocksdb_db, "compact", (METHOD)rocksdb_db_compact, -1);
+    rb_define_method(cRocksdb_db, "is_readonly?", (METHOD)rocksdb_db_is_readonly, 0);
+    rb_define_method(cRocksdb_db, "is_open?", (METHOD)rocksdb_db_is_open, 0);
 
     rb_define_method(cRocksdb_db, "iterator", (METHOD)rocksdb_db_each, 0);
     rb_define_method(cRocksdb_db, "each_index", (METHOD)rocksdb_db_each_index, 0);

lib/rocksdb.rb

@@ -26,12 +26,10 @@ def get_instance *args
     def initialize *args
       readonly = !!(args[1] && args[1][:readonly])
       @key = args[0]
-
       if !readonly and @@cache[@key]
         __initialize2(*args)
         raise DBError.new("error #{@key.to_s} alread open")
       end
-
       __initialize(*args)
       unless readonly
         @@cache[@key] = self

spec/db_readonly_spec.rb

@@ -7,15 +7,16 @@
     @rocksdb = RocksDB::DB.new "/tmp/file2"
     @rocksdb.put("test:multi_db", "1")
     @rocksdb.close
-
-    @rocksdb2 = RocksDB::DB.new "/tmp/file2", {:readonly => true}
+    
+    @rocksdb2 = RocksDB::DB.new("/tmp/file2", {:readonly => true})
   end
 
   it 'should get data' do
     expect{@rocksdb2.put("test:multi_db", "10")}.to raise_error(RuntimeError)
     expect{@rocksdb2.delete("test:multi_db")}.to raise_error(RuntimeError)
     expect(@rocksdb2.get("test:multi_db")).to eq "1"
-
+    expect(@rocksdb2.is_readonly?).to eq true
+
     batch = RocksDB::Batch.new
     batch.delete("test:batch1")
     batch.put("test:batch2", "b")

spec/db_spec.rb

@@ -4,11 +4,12 @@
 
 describe RocksDB do
   before do
-    @rocksdb = RocksDB::DB.new "/tmp/file"
+    @rocksdb = RocksDB::DB.new("/tmp/file")
   end
 
   it 'should get data' do
     @rocksdb.put("test:read", "1")
+    expect(@rocksdb.is_readonly?).to eq false
     expect(@rocksdb.get("test:read")).to eq "1"
   end
 
@@ -50,8 +51,7 @@
   end
 
   it 'should use multiple db' do
-    @rocksdb2 = RocksDB::DB.new "/tmp/file2"
-
+    @rocksdb2 = RocksDB::DB.new("/tmp/file2")
     @rocksdb.put("test:multi_db", "1")
     @rocksdb2.put("test:multi_db", "2")
 
@@ -120,34 +120,55 @@
     key = "test"
     value = "1"
 
-    expect{RocksDB::DB.new "/tmp/file"}.to raise_error(RocksDB::DBError)
+    expect{RocksDB::DB.new("/tmp/file")}.to raise_error(RocksDB::DBError)
 
     expect(@rocksdb.put("test:put", "1")).to be true
 
-    @rocksdb2 = RocksDB::DB.new "/tmp/file", {:readonly => true}
+    @rocksdb2 = RocksDB::DB.new("/tmp/file", {:readonly => true})
+    expect(@rocksdb2.is_readonly?).to eq true
     expect(@rocksdb2.get("test:put")).to eq "1"
 
     @rocksdb.close
-    @rocksdb = RocksDB::DB.new "/tmp/file"
+
+    expect(@rocksdb.is_open?).to eq false
+
+    @rocksdb = RocksDB::DB.new("/tmp/file")
+    expect(@rocksdb.is_readonly?).to eq false
+    expect(@rocksdb.is_open?).to eq true
     expect(@rocksdb.put("test:put", "2")).to be true
 
-    @rocksdb3 = RocksDB::DB.new "/tmp/file", {:readonly => true}
+    @rocksdb3 = RocksDB::DB.new("/tmp/file", {:readonly => true})
+    expect(@rocksdb3.is_readonly?).to eq true
+    expect(@rocksdb3.is_open?).to eq true
     expect(@rocksdb3.get("test:put")).to eq "2"
+
+    @rocksdb2.close
+    @rocksdb3.close
 
   end
 
   it 'singleton' do
     @rocksdb2 = RocksDB::DB.get_instance("/tmp/file")
+    expect(@rocksdb2.is_readonly?).to eq false
+    expect(@rocksdb2.is_open?).to eq true
+
     @rocksdb3 = RocksDB::DB.get_instance("/tmp/file")
+    expect(@rocksdb3.is_readonly?).to eq false
     expect(@rocksdb).to eq (@rocksdb3)
     expect(@rocksdb2).to eq (@rocksdb3)
 
     @rocksdb4 = RocksDB::DB.get_instance("/tmp/file", {:readonly => true})
     expect(@rocksdb2).not_to eq (@rocksdb4)
-
+    expect(@rocksdb4.is_readonly?).to eq true
+    expect(@rocksdb4.is_open?).to eq true
+
     @rocksdb2.close
     expect{@rocksdb2.get("test:put")}.to raise_error(RuntimeError)
+    expect(@rocksdb2.is_open?).to eq false
     expect{@rocksdb3.get("test:put")}.to raise_error(RuntimeError)
+    expect(@rocksdb3.is_open?).to eq false
+
+    @rocksdb4.close
   end
 
   context 'compact' do