Package org.postgresql.pljava.example.annotation

Class ThreadTest

java.lang.Object

org.postgresql.pljava.example.annotation.ThreadTest

All Implemented Interfaces:

Runnable

@SQLAction(implementor="notFromDDR",
           requires="strictlyNestedTest fn",
           install="select strictlyNestedTest()")
public class ThreadTest
extends Object
implements Runnable

Test control of access to 1-thread backend by n-thread JVM. The "select strictlyNestedTest()" is marked "notFromDDR" because it actually does deadlock when invoked from within install_jar, though it succeeds when invoked directly. The explanation may lie in the JNI spec's caveat that JNI MonitorEnter/MonitorExit functions must be paired with each other and not arbitrarily mixed with JVM monitorenter/monitorexit bytecodes. In the present design, that can happen (install_jar uses a synchronized block to call into the backend when executing DDR commands; DDR command calling strictlyNestedTest leads to JNI MonitorExit in BEGIN_CALL; perhaps that does not effectively release the lock taken by the synchronized block).

Constructor Summary

Constructors

Constructor	Description
ThreadTest()

Method Summary

Modifier and Type	Method	Description
void	run()
static String	strictlyNestedTest()	Test that another thread can enter SPI while the calling thread is out.

Methods inherited from class java.lang.Object

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

Constructor Details

ThreadTest

public ThreadTest()

Method Details

strictlyNestedTest

@Function(provides="strictlyNestedTest fn")
public static String strictlyNestedTest()
                                 throws SQLException

Test that another thread can enter SPI while the calling thread is out. Create a thread that uses SPI to perform a query and set the value of result. Start and wait for that thread (so this one is clearly out of the backend the whole time), then return the result.

Throws:

SQLException

run

public void run()

Specified by:

run in interface Runnable