XL: GetObject caching implemented for XL. (#2017)

The object cache implementation is XL cache, which defaults
to 8GB worth of read cache. Currently GetObject() transparently
writes to this cache upon first client read and then subsequently
serves reads from the same cache.

Currently expiration is not implemented.

strconv-bytes_test.go

@@ -0,0 +1,112 @@
+/*
+ * 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 "testing"
+
+// Tests various variants in supporting all the byte conversions.
+func TestByteConv(t *testing.T) {
+	// List of all tests for testing notation to corresponding
+	// byte conversions.
+	tests := []struct {
+		in  string
+		exp uint64
+	}{
+		// Using IEC notation.
+		{"42", 42},
+		{"42MB", 42000000},
+		{"42MiB", 44040192},
+		{"42mb", 42000000},
+		{"42mib", 44040192},
+		{"42MIB", 44040192},
+		{"42 MB", 42000000},
+		{"42 MiB", 44040192},
+		{"42 mb", 42000000},
+		{"42 mib", 44040192},
+		{"42 MIB", 44040192},
+		{"42.5MB", 42500000},
+		{"42.5MiB", 44564480},
+		{"42.5 MB", 42500000},
+		{"42.5 MiB", 44564480},
+		// Using SI notation.
+		{"42M", 42000000},
+		{"42Mi", 44040192},
+		{"42m", 42000000},
+		{"42mi", 44040192},
+		{"42MI", 44040192},
+		{"42 M", 42000000},
+		{"42 Mi", 44040192},
+		{"42 m", 42000000},
+		{"42 mi", 44040192},
+		{"42 MI", 44040192},
+		// With decimal values.
+		{"42.5M", 42500000},
+		{"42.5Mi", 44564480},
+		{"42.5 M", 42500000},
+		{"42.5 Mi", 44564480},
+		// With no more digits after '.'
+		{"42.M", 42000000},
+		{"42.Mi", 44040192},
+		{"42. m", 42000000},
+		{"42. mi", 44040192},
+		{"42. M", 42000000},
+		{"42. Mi", 44040192},
+		// Large testing, breaks when too much larger than this.
+		{"12.5 EB", uint64(12.5 * float64(EByte))},
+		{"12.5 E", uint64(12.5 * float64(EByte))},
+		{"12.5 EiB", uint64(12.5 * float64(EiByte))},
+	}
+
+	// Tests all notation variants.
+	for _, p := range tests {
+		got, err := strconvBytes(p.in)
+		if err != nil {
+			t.Errorf("Couldn't parse %v: %v", p.in, err)
+		}
+		if got != p.exp {
+			t.Errorf("Expected %v for %v, got %v", p.exp, p.in, got)
+		}
+	}
+}
+
+// Validates different types of input errors.
+func TestByteErrors(t *testing.T) {
+	// Input with integer and double space between notations.
+	got, err := strconvBytes("84 JB")
+	if err == nil {
+		t.Errorf("Expected error, got %v", got)
+	}
+	// Empty string.
+	got, err = strconvBytes("")
+	if err == nil {
+		t.Errorf("Expected error parsing nothing")
+	}
+	// Too large.
+	got, err = strconvBytes("16 EiB")
+	if err == nil {
+		t.Errorf("Expected error, got %v", got)
+	}
+}
+
+// Add benchmarks here.
+
+// Benchmarks for bytes converter.
+func BenchmarkParseBytes(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		strconvBytes("16.5 GB")
+	}
+}