XL/PutObject: Add single putObject and multipart caching. (#2115)

- Additionally adds test cases as well for object cache.
- Adds auto-expiry with expiration and cleanup time interval.

Fixes #2080
Fixes #2091

pkg/objcache/objcache_test.go

@@ -0,0 +1,172 @@
+/*
+ * Minio Cloud Storage, (C) 2016 Minio, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package objcache
+
+import (
+	"bytes"
+	"io"
+	"io/ioutil"
+	"testing"
+	"time"
+)
+
+// TestObjCache - tests various cases for object cache behavior.
+func TestObjCache(t *testing.T) {
+	// Non exhaustive list of all object cache behavior cases.
+	testCases := []struct {
+		expiry    time.Duration
+		cacheSize uint64
+		err       error
+		closeErr  error
+	}{
+		// Validate if a key is not found in cache and Open fails.
+		{
+			expiry:    NoExpiry,
+			cacheSize: 1024,
+			err:       ErrKeyNotFoundInCache,
+		},
+		// Validate if cache indicates that it is full and Create fails.
+		{
+			expiry:    NoExpiry,
+			cacheSize: 1,
+			err:       ErrCacheFull,
+		},
+		// Validate if Create succeeds but Close fails to write to buffer.
+		{
+			expiry:    NoExpiry,
+			cacheSize: 2,
+			closeErr:  io.ErrShortBuffer,
+		},
+		// Validate that Create and Close succeed, making sure to update the cache.
+		{
+			expiry:    NoExpiry,
+			cacheSize: 1024,
+		},
+		// Validate that Delete succeeds and Open fails with key not found in cache.
+		{
+			expiry:    NoExpiry,
+			cacheSize: 1024,
+			err:       ErrKeyNotFoundInCache,
+		},
+		// Validate OnEviction function is called upon entry delete.
+		{
+			expiry:    NoExpiry,
+			cacheSize: 1024,
+		},
+	}
+
+	// Test 1 validating Open failure.
+	testCase := testCases[0]
+	cache := New(testCase.cacheSize, testCase.expiry)
+	_, err := cache.Open("test")
+	if testCase.err != err {
+		t.Errorf("Test case 2 expected to pass, failed instead %s", err)
+	}
+
+	// Test 2 validating Create failure.
+	testCase = testCases[1]
+	cache = New(testCase.cacheSize, testCase.expiry)
+	_, err = cache.Create("test", 2)
+	if testCase.err != err {
+		t.Errorf("Test case 2 expected to pass, failed instead %s", err)
+	}
+
+	// Test 3 validating Create succeeds and returns a writer.
+	// Subsequently we Close() without writing any data, to receive
+	// `io.ErrShortBuffer`
+	testCase = testCases[2]
+	cache = New(testCase.cacheSize, testCase.expiry)
+	w, err := cache.Create("test", 1)
+	if testCase.err != err {
+		t.Errorf("Test case 3 expected to pass, failed instead %s", err)
+	}
+	if err = w.Close(); err != testCase.closeErr {
+		t.Errorf("Test case 3 expected to pass, failed instead %s", err)
+	}
+
+	// Test 4 validates Create and Close succeeds successfully caching
+	// the writes.
+	testCase = testCases[3]
+	cache = New(testCase.cacheSize, testCase.expiry)
+	w, err = cache.Create("test", 5)
+	if testCase.err != err {
+		t.Errorf("Test case 4 expected to pass, failed instead %s", err)
+	}
+	// Write '5' bytes.
+	w.Write([]byte("Hello"))
+	// Close to successfully save into cache.
+	if err = w.Close(); err != nil {
+		t.Errorf("Test case 4 expected to pass, failed instead %s", err)
+	}
+	r, err := cache.Open("test")
+	if err != nil {
+		t.Errorf("Test case 4 expected to pass, failed instead %s", err)
+	}
+	// Reads everything stored for key "test".
+	cbytes, err := ioutil.ReadAll(r)
+	if err != nil {
+		t.Errorf("Test case 4 expected to pass, failed instead %s", err)
+	}
+	// Validate if read bytes match.
+	if !bytes.Equal(cbytes, []byte("Hello")) {
+		t.Errorf("Test case 4 expected to pass. wanted \"Hello\", got %s", string(cbytes))
+	}
+
+	// Test 5 validates Delete succeeds and Open fails with err
+	testCase = testCases[4]
+	cache = New(testCase.cacheSize, testCase.expiry)
+	w, err = cache.Create("test", 5)
+	if err != nil {
+		t.Errorf("Test case 5 expected to pass, failed instead %s", err)
+	}
+	// Write '5' bytes.
+	w.Write([]byte("Hello"))
+	// Close to successfully save into cache.
+	if err = w.Close(); err != nil {
+		t.Errorf("Test case 5 expected to pass, failed instead %s", err)
+	}
+	// Delete the cache entry.
+	cache.Delete("test")
+	_, err = cache.Open("test")
+	if testCase.err != err {
+		t.Errorf("Test case 5 expected to pass, failed instead %s", err)
+	}
+
+	// Test 6 validates OnEviction being called upon Delete is being invoked.
+	testCase = testCases[5]
+	cache = New(testCase.cacheSize, testCase.expiry)
+	w, err = cache.Create("test", 5)
+	if err != nil {
+		t.Errorf("Test case 6 expected to pass, failed instead %s", err)
+	}
+	// Write '5' bytes.
+	w.Write([]byte("Hello"))
+	// Close to successfully save into cache.
+	if err = w.Close(); err != nil {
+		t.Errorf("Test case 6 expected to pass, failed instead %s", err)
+	}
+	var deleteKey string
+	cache.OnEviction = func(key string) {
+		deleteKey = key
+	}
+	// Delete the cache entry.
+	cache.Delete("test")
+	if deleteKey != "test" {
+		t.Errorf("Test case 6 expected to pass, wanted \"test\", got %s", deleteKey)
+	}
+}