HADOOP-17559. S3guard import OOM.

[steveloughran]

Remove all tracking of files from DDB AncestorState; dirs in import tool.

Reduces size of the cache to O(dirs).

Test change is to reduce brittleness to clock skew on loaded test runs;
removes an intermittent failure where the existence assert was triggering
a s3guard update -which then broke the assert about the number of writes

Change-Id: I9251f64beb0fec225b0b4ba71bc16f3e116bc758

[steveloughran]

tested: s3 london with s3guard. Some failures I'm fixing in the audit patch; only new failure was the intermittent one in ITestCommitOperations which I suspected was a regression, but tracked it down in the logs to clock skew: initial PUT of the output file uses local clock, but s3 uses its clock, and on HEAD request this is updated.

[steveloughran]

Stack from the test failure fixed here as seen in the audit PR. Shows its not directly related to this, though I had to stop through to make sure

java.lang.AssertionError: Number of records written after commit #2; first commit had 4; first commit ancestors CommitContext{operationState=AncestorState{operation=Commitid=55; dest=s3a://stevel-london/fork-0001/test/DELAY_LISTING_ME/testBulkCommitFiles/out; size=6; paths={s3a://stevel-london/fork-0001/test/DELAY_LISTING_ME s3a://stevel-london/fork-0001/test/DELAY_LISTING_ME/testBulkCommitFiles/out/file1 s3a://stevel-london/fork-0001 s3a://stevel-london/fork-0001/test/DELAY_LISTING_ME/testBulkCommitFiles/out s3a://stevel-london/fork-0001/test s3a://stevel-london/fork-0001/test/DELAY_LISTING_ME/testBulkCommitFiles}}}; second commit ancestors: CommitContext{operationState=AncestorState{operation=Commitid=55; dest=s3a://stevel-london/fork-0001/test/DELAY_LISTING_ME/testBulkCommitFiles/out; size=8; paths={s3a://stevel-london/fork-0001/test/DELAY_LISTING_ME s3a://stevel-london/fork-0001/test/DELAY_LISTING_ME/testBulkCommitFiles/out/file1 s3a://stevel-london/fork-0001 s3a://stevel-london/fork-0001/test/DELAY_LISTING_ME/testBulkCommitFiles/out s3a://stevel-london/fork-0001/test/DELAY_LISTING_ME/testBulkCommitFiles/out/subdir s3a://stevel-london/fork-0001/test s3a://stevel-london/fork-0001/test/DELAY_LISTING_ME/testBulkCommitFiles s3a://stevel-london/fork-0001/test/DELAY_LISTING_ME/testBulkCommitFiles/out/subdir/file2}}}: s3guard_metadatastore_record_writes expected:<2> but was:<3>
	at org.junit.Assert.fail(Assert.java:88)
	at org.junit.Assert.failNotEquals(Assert.java:834)
	at org.junit.Assert.assertEquals(Assert.java:645)
	at org.apache.hadoop.fs.s3a.S3ATestUtils$MetricDiff.assertDiffEquals(S3ATestUtils.java:1001)
	at org.apache.hadoop.fs.s3a.commit.ITestCommitOperations.testBulkCommitFiles(ITestCommitOperations.java:722)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
	at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
	at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:27)
	at org.junit.rules.TestWatcher$1.evaluate(TestWatcher.java:55)
	at org.junit.internal.runners.statements.FailOnTimeout$CallableStatement.call(FailOnTimeout.java:298)
	at org.junit.internal.runners.statements.FailOnTimeout$CallableStatement.call(FailOnTimeout.java:292)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at java.lang.Thread.run(Thread.java:748)

[steveloughran]

+Add a test to verify we can import with spaces in the filenames

[steveloughran]

closing as unmerged; leaving the PR up