Added logbuffer helper package
This adds a small package which is used to store logs for other
binaries we're calling. It's an in-memory non-depleting ring buffer
capable of directly taking in a stream (for example from stdout).
For reliability it has bounded total memory consumption.
It offers a simple interface to get the last n log lines out.
Test Plan: Has 100% test coverage built-in
Bug: T667
X-Origin-Diff: phab/D442
GitOrigin-RevId: 32d5944650793b6cea8ec48a40ea4abb3944ad21
diff --git a/core/pkg/logbuffer/logbuffer_test.go b/core/pkg/logbuffer/logbuffer_test.go
new file mode 100644
index 0000000..c38d7a6
--- /dev/null
+++ b/core/pkg/logbuffer/logbuffer_test.go
@@ -0,0 +1,94 @@
+// Copyright 2020 The Monogon Project Authors.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+// 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 logbuffer
+
+import (
+ "testing"
+
+ "github.com/stretchr/testify/require"
+)
+
+func TestSingleLine(t *testing.T) {
+ buf := New(1, 16000)
+ buf.Write([]byte("Hello World\n"))
+ out := buf.ReadLines(1)
+ require.Len(t, out, 1, "Invalid number of lines read")
+ require.Equal(t, "Hello World", out[0].Data, "Read bad log line")
+ require.Equal(t, 11, out[0].OriginalLength, "Invalid line length")
+}
+
+func TestPartialWritesAndReads(t *testing.T) {
+ buf := New(2, 16000)
+ buf.Write([]byte("Hello "))
+ buf.Write([]byte("World\nTest "))
+ buf.Write([]byte("2\n"))
+
+ out := buf.ReadLines(1)
+ require.Len(t, out, 1, "Invalid number of lines for partial read")
+ require.Equal(t, "Test 2", out[0].Data, "Read bad log line")
+
+ out2 := buf.ReadLines(2)
+ require.Len(t, out2, 2, "Invalid number of lines read")
+ require.Equal(t, "Hello World", out2[0].Data, "Read bad log line")
+ require.Equal(t, "Test 2", out2[1].Data, "Read bad log line")
+}
+
+func TestBufferOverwrite(t *testing.T) {
+ buf := New(3, 16000)
+ buf.Write([]byte("Test1\nTest2\nTest3\nTest4\n"))
+
+ out := buf.ReadLines(3)
+ require.Equal(t, out[0].Data, "Test2", "Read bad log line")
+ require.Equal(t, out[1].Data, "Test3", "Read bad log line")
+ require.Equal(t, out[2].Data, "Test4", "Overwritten data is invalid")
+}
+
+func TestTooLargeRequests(t *testing.T) {
+ buf := New(1, 16000)
+ outEmpty := buf.ReadLines(1)
+ require.Len(t, outEmpty, 0, "Returned more data than there is")
+
+ buf.Write([]byte("1\n2\n"))
+ out := buf.ReadLines(2)
+ require.Len(t, out, 1, "Returned more data than the ring buffer can hold")
+}
+
+func TestSpecialCases(t *testing.T) {
+ buf := New(2, 16000)
+ buf.Write([]byte("Test1"))
+ buf.Write([]byte("\nTest2\n"))
+ out := buf.ReadLines(2)
+ require.Len(t, out, 2, "Too many lines written")
+ require.Equal(t, out[0].Data, "Test1", "Read bad log line")
+ require.Equal(t, out[1].Data, "Test2", "Read bad log line")
+}
+
+func TestLineLengthLimit(t *testing.T) {
+ buf := New(2, 6)
+
+ testStr := "Just Testing"
+
+ buf.Write([]byte(testStr + "\nShort\n"))
+
+ out := buf.ReadLines(2)
+ require.Equal(t, len(testStr), out[0].OriginalLength, "Line is over length limit")
+ require.Equal(t, "Just T", out[0].Data, "Log line not properly truncated")
+
+ out2 := buf.ReadLinesTruncated(2, "...")
+ require.Equal(t, out2[0], "Just T...", "Line is over length limit")
+ require.Equal(t, out2[1], "Short", "Truncated small enough line")
+}