com.bigdata.concurrent

Class LockManager<R extends Comparable<R>>

java.lang.Object

com.bigdata.concurrent.LockManager<R>

Deprecated.

This implementation manages locks in terms of threads. A thread is required in order for a task to contend for its locks. This places a strain on the thread scheduler.

public class LockManager<R extends Comparable<R>>
extends Object

This class coordinates a schedule among concurrent operations requiring exclusive access to shared resources. Whenever possible, the result is a concurrent schedule - that is, operations having non-overlapping lock requirements run concurrently while operations that have lock contentions are queued behind operations that currently have locks on the relevant resources. A ResourceQueue is created for each resource and used to block operations that are awaiting a lock. When locks are not being pre-declared, a WAITS_FOR graph is additionally used to detect deadlocks.

Version:

$Id$

Author:

Bryan Thompson

Field Summary

Fields

Modifier and Type	Field and Description
protected boolean	DEBUG Deprecated. True iff the log level is DEBUG or less.
protected boolean	INFO Deprecated. True iff the log level is INFO or less.
protected static org.apache.log4j.Logger	log Deprecated.

Constructor Summary

Constructors

Constructor and Description
LockManager(int maxConcurrency, boolean predeclareLocks) Deprecated. Create a lock manager for resources and concurrent operations.

Method Summary

Methods

Modifier and Type	Method and Description
CounterSet	getCounters() Deprecated.
String	toString() Deprecated.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

log

protected static final org.apache.log4j.Logger log

Deprecated.

INFO

protected final boolean INFO

Deprecated.

True iff the log level is INFO or less.

DEBUG

protected final boolean DEBUG

Deprecated.

True iff the log level is DEBUG or less.

Constructor Detail

LockManager

public LockManager(int maxConcurrency,
           boolean predeclareLocks)

Deprecated.

Create a lock manager for resources and concurrent operations.

Note that there is no concurrency limit imposed by the LockManager when predeclareLocks is true as deadlocks are impossible and we do not maintain a WAITS_FOR graph.

Parameters:

maxConcurrency - The maximum multi-programming level (ignored if predeclareLocks is true).

predeclareLocks - When true operations MUST declare all locks before they begin to execute. This makes possible several efficiencies and by sorting the resources in each lock request into a common order we are able to avoid deadlocks entirely.

Method Detail

getCounters

public CounterSet getCounters()

Deprecated.

toString

public String toString()

Deprecated.

Overrides:

toString in class Object