Refactor TemporaryBuffer to support reuse in other contexts

Later we are going to add support for smart HTTP, which requires us to
buffer at least some of the request created by a client before we ship
it to the server.  For many requests, we can fit it completely into a
1 MiB buffer, but if it doesn't we can drop back to using the chunked
transfer encoding to send an unknown stream length.

Rather than recoding the block based memory buffer, we refactor the
local file overflow strategy into a subclass, allowing the HTTP client
code to replace this portion of the logic with its own approach to
start the chunked encoding request.

Change-Id: Iac61ea1017b14e0ad3c4425efc3d75718b71bb8e
Signed-off-by: Shawn O. Pearce <sop@google.com>

2 files changed, 27 insertions, 15 deletions

diff --git a/org.eclipse.jgit.test/exttst/org/eclipse/jgit/patch/EGitPatchHistoryTest.java b/org.eclipse.jgit.test/exttst/org/eclipse/jgit/patch/EGitPatchHistoryTest.java
index 60d3853d85..ae9fb0ef50 100644
--- a/org.eclipse.jgit.test/exttst/org/eclipse/jgit/patch/EGitPatchHistoryTest.java
+++ b/org.eclipse.jgit.test/exttst/org/eclipse/jgit/patch/EGitPatchHistoryTest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2008, Google Inc.
+ * Copyright (C) 2008-2009, Google Inc.
  * and other copyright owners as documented in the project's IP log.
  *
  * This program and the accompanying materials are made available
@@ -211,7 +211,7 @@ public class EGitPatchHistoryTest extends TestCase {
 						buf.destroy();
 					}
 					commitId = line.substring("commit ".length());
-					buf = new TemporaryBuffer();
+					buf = new TemporaryBuffer.LocalFile();
 				} else if (buf != null) {
 					buf.write(line.getBytes("ISO-8859-1"));
 					buf.write('\n');
diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/util/TemporaryBufferTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/util/TemporaryBufferTest.java
index e1f802b3d1..ea1fd7313d 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/util/TemporaryBufferTest.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/util/TemporaryBufferTest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2008, Google Inc.
+ * Copyright (C) 2008-2009, Google Inc.
  * and other copyright owners as documented in the project's IP log.
  *
  * This program and the accompanying materials are made available
@@ -54,7 +54,7 @@ import junit.framework.TestCase;
 
 public class TemporaryBufferTest extends TestCase {
 	public void testEmpty() throws IOException {
-		final TemporaryBuffer b = new TemporaryBuffer();
+		final TemporaryBuffer b = new TemporaryBuffer.LocalFile();
 		try {
 			b.close();
 			assertEquals(0, b.length());
@@ -67,7 +67,7 @@ public class TemporaryBufferTest extends TestCase {
 	}
 
 	public void testOneByte() throws IOException {
-		final TemporaryBuffer b = new TemporaryBuffer();
+		final TemporaryBuffer b = new TemporaryBuffer.LocalFile();
 		final byte test = (byte) new TestRng(getName()).nextInt();
 		try {
 			b.write(test);
@@ -93,7 +93,7 @@ public class TemporaryBufferTest extends TestCase {
 	}
 
 	public void testOneBlock_BulkWrite() throws IOException {
-		final TemporaryBuffer b = new TemporaryBuffer();
+		final TemporaryBuffer b = new TemporaryBuffer.LocalFile();
 		final byte[] test = new TestRng(getName())
 				.nextBytes(TemporaryBuffer.Block.SZ);
 		try {
@@ -123,7 +123,7 @@ public class TemporaryBufferTest extends TestCase {
 	}
 
 	public void testOneBlockAndHalf_BulkWrite() throws IOException {
-		final TemporaryBuffer b = new TemporaryBuffer();
+		final TemporaryBuffer b = new TemporaryBuffer.LocalFile();
 		final byte[] test = new TestRng(getName())
 				.nextBytes(TemporaryBuffer.Block.SZ * 3 / 2);
 		try {
@@ -153,7 +153,7 @@ public class TemporaryBufferTest extends TestCase {
 	}
 
 	public void testOneBlockAndHalf_SingleWrite() throws IOException {
-		final TemporaryBuffer b = new TemporaryBuffer();
+		final TemporaryBuffer b = new TemporaryBuffer.LocalFile();
 		final byte[] test = new TestRng(getName())
 				.nextBytes(TemporaryBuffer.Block.SZ * 3 / 2);
 		try {
@@ -181,7 +181,7 @@ public class TemporaryBufferTest extends TestCase {
 	}
 
 	public void testOneBlockAndHalf_Copy() throws IOException {
-		final TemporaryBuffer b = new TemporaryBuffer();
+		final TemporaryBuffer b = new TemporaryBuffer.LocalFile();
 		final byte[] test = new TestRng(getName())
 				.nextBytes(TemporaryBuffer.Block.SZ * 3 / 2);
 		try {
@@ -210,7 +210,7 @@ public class TemporaryBufferTest extends TestCase {
 	}
 
 	public void testLarge_SingleWrite() throws IOException {
-		final TemporaryBuffer b = new TemporaryBuffer();
+		final TemporaryBuffer b = new TemporaryBuffer.LocalFile();
 		final byte[] test = new TestRng(getName())
 				.nextBytes(TemporaryBuffer.DEFAULT_IN_CORE_LIMIT * 3);
 		try {
@@ -237,7 +237,7 @@ public class TemporaryBufferTest extends TestCase {
 	}
 
 	public void testInCoreLimit_SwitchOnAppendByte() throws IOException {
-		final TemporaryBuffer b = new TemporaryBuffer();
+		final TemporaryBuffer b = new TemporaryBuffer.LocalFile();
 		final byte[] test = new TestRng(getName())
 				.nextBytes(TemporaryBuffer.DEFAULT_IN_CORE_LIMIT + 1);
 		try {
@@ -265,7 +265,7 @@ public class TemporaryBufferTest extends TestCase {
 	}
 
 	public void testInCoreLimit_SwitchBeforeAppendByte() throws IOException {
-		final TemporaryBuffer b = new TemporaryBuffer();
+		final TemporaryBuffer b = new TemporaryBuffer.LocalFile();
 		final byte[] test = new TestRng(getName())
 				.nextBytes(TemporaryBuffer.DEFAULT_IN_CORE_LIMIT * 3);
 		try {
@@ -293,7 +293,7 @@ public class TemporaryBufferTest extends TestCase {
 	}
 
 	public void testInCoreLimit_SwitchOnCopy() throws IOException {
-		final TemporaryBuffer b = new TemporaryBuffer();
+		final TemporaryBuffer b = new TemporaryBuffer.LocalFile();
 		final byte[] test = new TestRng(getName())
 				.nextBytes(TemporaryBuffer.DEFAULT_IN_CORE_LIMIT * 2);
 		try {
@@ -324,7 +324,7 @@ public class TemporaryBufferTest extends TestCase {
 	}
 
 	public void testDestroyWhileOpen() throws IOException {
-		final TemporaryBuffer b = new TemporaryBuffer();
+		final TemporaryBuffer b = new TemporaryBuffer.LocalFile();
 		try {
 			b.write(new TestRng(getName())
 					.nextBytes(TemporaryBuffer.DEFAULT_IN_CORE_LIMIT * 2));
@@ -334,7 +334,7 @@ public class TemporaryBufferTest extends TestCase {
 	}
 
 	public void testRandomWrites() throws IOException {
-		final TemporaryBuffer b = new TemporaryBuffer();
+		final TemporaryBuffer b = new TemporaryBuffer.LocalFile();
 		final TestRng rng = new TestRng(getName());
 		final int max = TemporaryBuffer.DEFAULT_IN_CORE_LIMIT * 2;
 		final byte[] expect = new byte[max];
@@ -379,4 +379,16 @@ public class TemporaryBufferTest extends TestCase {
 		}
 	}
 
+	public void testHeap() throws IOException {
+		final TemporaryBuffer b = new TemporaryBuffer.Heap(2 * 8 * 1024);
+		final byte[] r = new byte[8 * 1024];
+		b.write(r);
+		b.write(r);
+		try {
+			b.write(1);
+			fail("accepted too many bytes of data");
+		} catch (IOException e) {
+			assertEquals("In-memory buffer limit exceeded", e.getMessage());
+		}
+	}
 }