external-software/github_OpenIdentityPlatform_OpenDJ.git

			@@ -105,27 +105,6 @@
			private static final int IMPORT_DB_CACHE_SIZE = 32 * MB;

			/**
			* Number of attempts a {@link WriteableStorageImpl#write} makes before it propagates the conflict to the caller.
			* <p>
			* It is a budget of attempts and not of time, so it is only ever reached by the conflicts that report quickly.
			* PersistIt reports a write-write conflict only once it has waited on it, up to
			* {@code SharedResource.DEFAULT_MAX_WAIT_TIME} - a minute, which this backend never lowers - so a conflict slower
			* to report than {@link #MAX_RETRY_WINDOW_NANOS} spends the whole window inside its first attempt, is granted the
			* single replay that window's exemption guarantees, and gives up on the window after two attempts rather than
			* after this many.
			*/
			static final int MAX_RETRIES = 10;

			/**
			* Wall-clock budget the replays of a {@link WriteableStorageImpl#write} may spend, in nanoseconds. It is checked
			* between attempts, so an attempt already running is never interrupted, and never before one replay has been
			* made: the loop returns after at most this window plus two attempts. It bounds the conflicts that are slow to
			* report, which {@link #MAX_RETRIES} alone does not - an operation whose own work takes seconds would otherwise
			* multiply that wait by the attempt count.
			*/
			static final long MAX_RETRY_WINDOW_NANOS = 10L * 1000L * 1000L * 1000L; //10 s

			/**
			* Upper bound of the random delay before the second attempt, in milliseconds; it doubles with every attempt. This
			* is the bound of the flat sleep this loop took before it was bounded, so the first replay is delayed exactly as
			* it was and only the later ones back off.
			@@ -135,6 +114,10 @@
			/** Upper bound the doubled delay is capped at, in milliseconds. */
			private static final double MAX_SLEEP_ON_RETRY_MS = 1000.0;

			/** Name of the property which bounds the replays of a {@link WriteableStorageImpl#write}, for the reports of it. */
			private static final String RETRY_TIME_LIMIT_PROPERTY =
			PDBBackendCfgDefn.getInstance().getDBTxnRetryTimeLimitPropertyDefinition().getName();

			private static final String VOLUME_NAME = "dj";
			private static final String JOURNAL_NAME = VOLUME_NAME + "_journal";
			/** The buffer / page size used by the PersistIt storage. */
			@@ -671,7 +654,10 @@
			{
			final Transaction txn = db.getTransaction();
			final long startedAt = System.nanoTime();
			final long giveUpAt = startedAt + retryWindowNanos;
			//read once, so that a change of the property applies from the next write on rather than to one in flight;
			//0 replays for as long as the conflict lasts
			final long retryTimeLimitMs = config.getDBTxnRetryTimeLimit();
			final long giveUpAt = startedAt + TimeUnit.MILLISECONDS.toNanos(retryTimeLimitMs);
			for (int attempt = 1;; attempt++)
			{
			final RollbackException conflict;
			@@ -705,24 +691,26 @@
			// decided and slept for outside the try statement: the sleep used to run before the finally ended the
			// rolled back transaction, holding it open for the whole backoff and lengthening the window every other
			// writer collides with
			//Bounded by time alone, and not by a count of attempts: a rollback is how persistit resolves two
			//transactions writing the same key - it waits for the other one to end and rolls this one back if that
			//one committed - so under concurrent writes to a hot key, such as an index key shared by entries below
			//the index entry limit, a healthy write loses several of these races in a row (#1149)
			//System.nanoTime() - giveUpAt is the overflow safe form of the comparison, and attempt > 1 keeps the
			//window from ending the loop before a single replay: persistit reports a write-write conflict only once
			//limit from ending the loop before a single replay: persistit reports a write-write conflict only once
			//it has waited on it, up to SharedResource.DEFAULT_MAX_WAIT_TIME - a minute, which this backend never
			//lowers - so one attempt can outlast the window on its own, and it is the attempt after that one which
			//lowers - so one attempt can outlast the limit on its own, and it is the attempt after that one which
			//is likeliest to succeed, the transaction that blocked it having just finished
			//one clock sample for both, so that the elapsed time reported is the one the give up was decided on
			final long now = System.nanoTime();
			final boolean capSpent = attempt >= maxRetries;
			if (capSpent \|\| (attempt > 1 && now - giveUpAt >= 0))
			if (retryTimeLimitMs > 0 && attempt > 1 && now - giveUpAt >= 0)
			{
			final long elapsedMs = TimeUnit.NANOSECONDS.toMillis(now - startedAt);
			//which of the two bounds was spent, so that the config change paths - which report this as the trailing
			//cause of a message of their own - say whether raising the attempts or the window is what would have helped
			final String boundSpent = capSpent ? "attempt cap" : "retry window";
			//names the property, so that the config change paths - which report this as the trailing cause of a
			//message of their own - say what would have helped
			final StorageRuntimeException spent = new StorageRuntimeException(
			"pdb: backend '" + config.getBackendId() + "' did not apply the transaction after " + attempt
			+ " attempts in " + elapsedMs + " ms, the " + boundSpent + " being spent; the last conflict was "
			+ conflict);
			+ " attempts in " + elapsedMs + " ms, the " + RETRY_TIME_LIMIT_PROPERTY + " of " + retryTimeLimitMs
			+ " ms being spent; the last conflict was " + conflict);
			// the conflict is suppressed rather than made the cause, because a cause is what every caller strips
			// this message off with: write(WriteOperation) below unwraps a StorageRuntimeException that carries one
			// and throws the cause in its place, and EntryContainer.throwAllowedExceptionTypes:1121 rethrows a
			@@ -732,17 +720,17 @@
			spent.addSuppressed(conflict);
			//warned once, at exhaustion only, unlike JDBCStorage which warns on every replay: a conflict is routine
			//on the ordinary add and modify path of this engine and a line per replay would flood the log. It names
			//the bound that was spent for the same reason the exception does, and it is the only rendering that can
			//carry the stack of the conflict: stackTraceToSingleLineString, the form the config change paths report
			//this exception with, walks the causes and never prints a suppressed exception
			//the property that was spent for the same reason the exception does, and it is the only rendering that
			//can carry the stack of the conflict: stackTraceToSingleLineString, the form the config change paths
			//report this exception with, walks the causes and never prints a suppressed exception
			logger.warn(LocalizableMessage.raw("pdb: giving up on the transaction of backend '%s' after %d attempts"
			+ " in %d ms, the %s being spent: %s", config.getBackendId(), attempt, elapsedMs, boundSpent,
			stackTraceToSingleLineString(conflict)));
			+ " in %d ms, the %s of %d ms being spent: %s", config.getBackendId(), attempt, elapsedMs,
			RETRY_TIME_LIMIT_PROPERTY, retryTimeLimitMs, stackTraceToSingleLineString(conflict)));
			throw spent;
			}
			if (logger.isTraceEnabled())
			{
			logger.trace("pdb: replaying the transaction after %s, attempt %d of %d", conflict, attempt, maxRetries);
			logger.trace("pdb: replaying the transaction after %s, attempt %d", conflict, attempt);
			}
			try
			{
			@@ -1030,10 +1018,6 @@
			private long configuredCacheSize;
			private long reservedCacheSize;
			private StorageStatus storageStatus = StorageStatus.working();
			/** Attempt bound of a {@link WriteableStorageImpl#write}, {@link #MAX_RETRIES} outside the tests. */
			private final int maxRetries;
			/** Wall-clock bound of a {@link WriteableStorageImpl#write}, {@link #MAX_RETRY_WINDOW_NANOS} outside the tests. */
			private final long retryWindowNanos;

			/**
			* Creates a new persistit storage with the provided configuration.
			@@ -1047,34 +1031,7 @@
			// FIXME: should be package private once importer is decoupled.
			public PDBStorage(final PDBBackendCfg cfg, ServerContext serverContext) throws ConfigException
			{
			this(cfg, serverContext, MAX_RETRIES, MAX_RETRY_WINDOW_NANOS);
			}

			/**
			* Creates a new persistit storage whose replay bounds are the given ones rather than {@link #MAX_RETRIES} and
			* {@link #MAX_RETRY_WINDOW_NANOS}.
			* <p>
			* Only a test builds one of these, and it does so to stop the two bounds racing each other: with the shipped
			* values a run of replays spends a random share of the window on backoff alone, so a test of the attempt cap
			* can be ended by the window on a loaded machine, and a test of the window has to spend seconds of build time
			* to reach it.
			*
			* @param cfg
			* The configuration.
			* @param serverContext
			* This server instance context
			* @param maxRetries
			* Number of attempts a write makes before it propagates the conflict to the caller.
			* @param retryWindowNanos
			* Wall-clock budget the replays of a write may spend, in nanoseconds.
			* @throws ConfigException if memory cannot be reserved
			*/
			PDBStorage(final PDBBackendCfg cfg, ServerContext serverContext, int maxRetries, long retryWindowNanos)
			throws ConfigException
			{
			this.serverContext = serverContext;
			this.maxRetries = maxRetries;
			this.retryWindowNanos = retryWindowNanos;
			backendDirectory = getBackendDirectory(cfg);
			runningDirectoryPermissions = cfg.getDBDirectoryPermissions();
			config = cfg;
			@@ -1293,15 +1250,17 @@
			/**
			* {@inheritDoc}
			* <p>
			* A transaction the engine rolled back is replayed, bounded twice: by {@link #MAX_RETRIES} attempts and by the
			* {@link #MAX_RETRY_WINDOW_NANOS} wall-clock window, whichever is spent first - except that the window alone
			* never ends the replays before one has been made. It is bounded because the
			* configuration change paths of the pluggable backend hold an entry container's exclusive lock across this
			* method, and every reader of that suffix then waits - untimed and uninterruptibly - until it returns, so a
			* conflict that never clears would park every worker thread of that suffix rather than fail one operation.
			* A transaction the engine rolled back is replayed for as long as the {@code db-txn-retry-time-limit} of the
			* backend allows - without limit when it is 0, its default - except that the limit never ends the replays before
			* one has been made. A rollback is how persistit resolves two transactions writing the same key, so a healthy
			* write under concurrent load can lose several of them in a row: a count of attempts failed such writes (#1149),
			* and the replays are bounded by time alone. Without a limit a write waits for its conflict to clear the way a
			* JE writer waits for a lock. A limit is for the configuration change paths of the pluggable backend, which hold
			* an entry container's exclusive lock across this method: every reader of that suffix then waits - untimed and
			* uninterruptibly - until it returns.
			* <p>
			* Once the bound is spent the conflict is reported as a {@link StorageRuntimeException} naming the backend, the
			* attempts spent, the time they took and which of the two bounds ran out. It carries the conflict as a
			* Once the limit is spent the conflict is reported as a {@link StorageRuntimeException} naming the backend, the
			* attempts spent, the time they took and the property whose value ran out. It carries the conflict as a
			* suppressed exception rather than as its cause: a cause is unwrapped below and thrown in its place, and
			* {@code EntryContainer.throwAllowedExceptionTypes} likewise passes a {@link StorageRuntimeException} through
			* untouched only while it has no cause. Given a cause, both hand the caller a bare RollbackException instead,