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Shaded version of DataStax Java Driver for Apache Cassandra
/*
* Copyright (C) 2009 Wayne Meissner
*
* This file is part of jffi.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*
* Alternatively, you can redistribute it and/or modify it under
* the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
* for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this work. If not, see magazines = Collections.synchronizedSet(new HashSet());
private final ConcurrentLinkedQueue freeQueue = new ConcurrentLinkedQueue();
private final ConcurrentLinkedQueue partialQueue = new ConcurrentLinkedQueue();
//
// Since the CallContext native handle is used by the native pool code
// a strong reference to the call context needs to be kept.
//
private final CallContext callContext;
ClosurePool(CallContext callContext) {
this.callContext = callContext;
}
synchronized void recycle(Magazine magazine) {
magazine.recycle();
if (!magazine.isEmpty()) {
useMagazine(magazine);
} else {
// If the magazine was empty during recycling, it means all the closures
// allocated from it set autorelease=false, so we cannot re-use it.
// Let GC clean it up.
magazines.remove(magazine);
}
}
void recycle(Magazine.Slot slot, MagazineHolder holder) {
partialQueue.add(new Handle(slot, holder));
}
private void useMagazine(Magazine m) {
MagazineHolder h = new MagazineHolder(this, m);
ArrayList handles = new ArrayList();
Magazine.Slot s;
ConcurrentLinkedQueue q = m.isFull() ? freeQueue : partialQueue;
while ((s = m.get()) != null) {
handles.add(new Handle(s, h));
}
q.addAll(handles);
}
public Closure.Handle newClosureHandle(Closure closure) {
Handle h = partialQueue.poll();
if (h == null) {
h = freeQueue.poll();
}
if (h == null) {
h = allocateNewHandle();
}
h.slot.proxy.closure = closure;
return h;
}
private Handle allocateNewHandle() {
Handle h;
while ((h = partialQueue.poll()) == null && (h = freeQueue.poll()) == null) {
Magazine m = new Magazine(callContext);
useMagazine(m);
magazines.add(m);
}
return h;
}
/**
* Manages the lifecycle of a native closure.
*
* Implements {@link Closure.Handle} interface.
*/
private static final class Handle implements Closure.Handle {
/**
* Keep references to the closure pool so it does not get garbage collected
* until all closures using it do.
*/
final MagazineHolder holder;
final Magazine.Slot slot;
private volatile boolean disposed;
/**
* Creates a new Handle to lifecycle manager the native closure.
*
* @param slot THe magazine slot this handle belongs to
* @param holder The magazine holder containing this handle
*/
Handle(Magazine.Slot slot, MagazineHolder holder) {
this.slot = slot;
this.holder = holder;
}
public long getAddress() {
if (disposed) {
throw new RuntimeException("trying to access disposed closure handle");
}
return slot.codeAddress;
}
public void setAutoRelease(boolean autorelease) {
if (!disposed) {
slot.autorelease = autorelease;
}
}
@Deprecated
public void free() {
dispose();
}
public synchronized void dispose() {
if (!disposed) {
disposed = true;
slot.autorelease = true;
slot.proxy.closure = NULL_CLOSURE;
holder.pool.recycle(slot, holder);
}
}
}
private static final class Magazine {
/** Store a reference to the MemoryIO accessor here for easy access */
private static final com.kenai.jffi.MemoryIO IO = com.kenai.jffi.MemoryIO.getInstance();
/** A handle to the foreign interface to keep it alive as long as this object is alive */
@SuppressWarnings({"FieldCanBeLocal", "UnusedDeclaration"})
private final Foreign foreign = Foreign.getInstance();
private final CallContext ctx;
private final long magazine;
private final Slot[] slots;
private int next;
private int freeCount;
Magazine(CallContext ctx) {
this.ctx = ctx;
this.magazine = foreign.newClosureMagazine(ctx.getAddress(), Proxy.METHOD, false);
ArrayList slots = new ArrayList();
for (;;) {
long h;
Proxy proxy = new Proxy(ctx);
if ((h = foreign.closureMagazineGet(magazine, proxy)) == 0) {
break;
}
Slot s = new Slot(h, proxy);
slots.add(s);
}
this.slots = new Slot[slots.size()];
slots.toArray(this.slots);
next = 0;
freeCount = this.slots.length;
}
Slot get() {
while (freeCount > 0 && next < slots.length) {
Slot s = slots[next++];
if (s.autorelease) {
freeCount--;
return s;
}
}
return null;
}
boolean isFull() {
return slots.length == freeCount;
}
boolean isEmpty() {
return freeCount < 1;
}
void recycle() {
for (int i = 0; i < slots.length; i++) {
Slot s = slots[i];
if (s.autorelease) {
freeCount++;
s.proxy.closure = NULL_CLOSURE;
}
}
next = 0;
}
@Override
protected void finalize() throws Throwable {
try {
boolean release = true;
//
// If any of the closures allocated from this magazine set autorelease=false
// then this magazine cannot be freed, so just let it leak
//
for (int i = 0; i < slots.length; i++) {
if (!slots[i].autorelease) {
release = false;
break;
}
}
if (magazine != 0 && release) {
foreign.freeClosureMagazine(magazine);
}
} finally {
super.finalize();
}
}
static final class Slot {
/**
* The address of the native closure structure.
*
* Note: This is NOT the code address, but a pointer to the structure
* which contains the code address.
*/
final long handle;
/** The code trampoline address */
final long codeAddress;
final Proxy proxy;
volatile boolean autorelease;
public Slot(long handle, Proxy proxy) {
this.handle = handle;
this.proxy = proxy;
this.autorelease = true;
codeAddress = IO.getAddress(handle);
}
}
}
private static final class MagazineHolder {
final ClosurePool pool;
final Magazine magazine;
public MagazineHolder(ClosurePool pool, Magazine magazine) {
this.pool = pool;
this.magazine = magazine;
}
@Override
protected void finalize() throws Throwable {
try {
pool.recycle(magazine);
} finally {
super.finalize();
}
}
}
/**
* This is a proxy passed to the native code, to be called by the
* native trampoline code.
*/
static final class Proxy {
static final Method METHOD = getMethod();
/**
* Keep references to the return and parameter types so they do not get
* garbage collected until the closure does.
*/
final CallContext callContext;
volatile Closure closure;
/**
* Gets the Method to be invoked by native code
*
* @return The method to be invoked by native code
*/
private static Method getMethod() {
try {
return Proxy.class.getDeclaredMethod("invoke", new Class[]{long.class, long.class});
} catch (Throwable ex) {
throw new RuntimeException(ex);
}
}
Proxy(CallContext callContext) {
this.closure = NULL_CLOSURE;
this.callContext = callContext;
}
/**
* Invoked by the native closure trampoline to execute the java side of
* the closure.
*
* @param retvalAddress The address of the native return value buffer
* @param paramAddress The address of the native parameter buffer.
*/
public void invoke(long retvalAddress, long paramAddress) {
closure.invoke(new DirectClosureBuffer(callContext, retvalAddress, paramAddress));
}
}
private static final Closure NULL_CLOSURE = new Closure() {
public void invoke(Buffer buffer) {
}
};
}
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