XL: Implement new ReadAll API for files which are read in single call. (#1974)

Add a unit test as well.

posix_test.go

@@ -0,0 +1,92 @@
+/*
+ * 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 main
+
+import (
+	"io/ioutil"
+	"os"
+	"testing"
+)
+
+// Tests the functionality implemented by ReadAll storage API.
+func TestReadAll(t *testing.T) {
+	path, err := ioutil.TempDir(os.TempDir(), "minio-")
+	if err != nil {
+		t.Fatalf("Unable to create a temporary directory, %s", err)
+	}
+	defer removeAll(path)
+
+	// Initialize posix storage layer.
+	posix, err := newPosix(path)
+	if err != nil {
+		t.Fatalf("Unable to initialize posix, %s", err)
+	}
+
+	// Create files for the test cases.
+	if err = posix.MakeVol("exists"); err != nil {
+		t.Fatalf("Unable to create a volume \"exists\", %s", err)
+	}
+	if err = posix.AppendFile("exists", "as-directory/as-file", []byte("Hello, World")); err != nil {
+		t.Fatalf("Unable to create a file \"as-directory/as-file\", %s", err)
+	}
+	if err = posix.AppendFile("exists", "as-file", []byte("Hello, World")); err != nil {
+		t.Fatalf("Unable to create a file \"as-file\", %s", err)
+	}
+
+	// Testcases to validate different conditions for ReadAll API.
+	testCases := []struct {
+		volume string
+		path   string
+		err    error
+	}{
+		// Validate volume does not exist.
+		{
+			"i-dont-exist",
+			"",
+			errVolumeNotFound,
+		},
+		// Validate bad condition file does not exist.
+		{
+			"exists",
+			"as-file-not-found",
+			errFileNotFound,
+		},
+		// Validate bad condition file exists as prefix/directory and
+		// we are attempting to read it.
+		{
+			"exists",
+			"as-directory",
+			errFileNotFound,
+		},
+		// Validate the good condition file exists and we are able to
+		// read it.
+		{
+			"exists",
+			"as-file",
+			nil,
+		},
+		// Add more cases here.
+	}
+
+	// Run through all the test cases and validate for ReadAll.
+	for i, testCase := range testCases {
+		_, err = posix.ReadAll(testCase.volume, testCase.path)
+		if err != testCase.err {
+			t.Errorf("Test %d expected err %s, got err %s", i+1, testCase.err, err)
+		}
+	}
+}