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Speaker : Arnaud Bos - @arnaud_bos
Project Loom : la concurrence au bout du fil
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#JSC2019 @arnaud_bos
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#JSC2019 @arnaud_bos
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#JSC2019 @arnaud_bos
private Connection.Available getConnection(long eta,
long wait,
String token)
{
for(;;) {
if (eta > MAX_ETA_MS) {
throw new EtaExceededException();
}
if (wait > 0) {
Thread.sleep(wait);
}
println("Retrying download after " + wait + "ms wait.");
Connection c = coordinator.requestConnection(token);
if (c instanceof Connection.Available) {
return (Connection.Available) c;
}
Connection.Unavailable unavail = (Connection.Unavailable) c;
eta = unavail.getEta();
wait = unavail.getWait();
token = unavail.getToken();
}
}
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#JSC2019 @arnaud_bos
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#JSC2019 @arnaud_bos
private void getThingy(int i, CompletionHandler handler) {
println("Start getThingy.");
getConnection(new CompletionHandler!<>() {
@Override
public void completed(Connection.Available conn) {
println("Got token, " + conn.getToken());
CompletableFuture downloadFut = new CompletableFuture!<>();
gateway.downloadThingy(new RequestHandler() {
private int total = 0;
private boolean pulsing = false;
private boolean cancelled = false;
@Override
public void received(byte[] data) {
int read = data.length;
println(i + " !:: Thingy received " + read);
if (!pulsing) {
Runnable pulse = new PulseRunnable(i, downloadFut, con
boundedPulseExecutor.schedule(pulse, 2_000L, TimeUnit.
pulsing = true;
}
!// !!... to be continued
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#JSC2019 @arnaud_bos
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#JSC2019 @arnaud_bos
public static void asyncNonBlockingRequest(ExecutorService executor,
String url, String headers,
RequestHandler handler) {
executor.submit(() !-> {
try {
println("Starting request to " + url);
URL uri = new URL(url);
SocketAddress serverAddress = new InetSocketAddress(uri.getHost(), 80);
AsynchronousSocketChannel channel = AsynchronousSocketChannel.open(group);
channel.connect(serverAddress, null, new CompletionHandler() {
@Override
public void completed(Void result, Void attachment) {
ByteBuffer headersBuffer = ByteBuffer.wrap((headers + "Host: " + uri.ge
ByteBuffer responseBuffer = ByteBuffer.allocate(1024);
channel.write(headersBuffer, headersBuffer, new CompletionHandler!<>() {
@Override
public void completed(Integer written, ByteBuffer attachment) {
if (attachment.hasRemaining()) {
channel.write(attachment, attachment, this);
} else {
channel.read(responseBuffer, responseBuffer, new Completion
@Override
public void completed(Integer read,
ByteBuffer attachment) {
!// More
!// this
!// way
!// !!==>
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#JSC2019 @arnaud_bos
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#JSC2019 @arnaud_bos
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#JSC2019 @arnaud_bos
private Mono getConnection(long eta, long wait, String
token) {
AtomicLong etaRef = new AtomicLong(eta);
AtomicLong waitRef = new AtomicLong(wait);
AtomicReference tokenRef = new AtomicReference!<>(token);
return Mono.defer(() !-> {
if (etaRef.get() > MAX_ETA_MS) {
return Mono.error(new EtaExceededException());
}
return Mono.delay(Duration.ofMillis(waitRef.get()))
.flatMap(i !-> coordinator.requestConnection(tokenRef.get()));
}).flatMap(c !-> {
if (c instanceof Connection.Available) {
return Mono.just((Connection.Available) c);
} else {
Connection.Unavailable unavail = (Connection.Unavailable) c;
etaRef.set(unavail.getEta());
waitRef.set(unavail.getWait());
tokenRef.set(unavail.getToken());
return Mono.empty();
}
}).repeatWhenEmpty(Repeat
.onlyIf(ctx !-> true)
.doOnRepeat(ctx !->
println(waitRef.get() + ", " + etaRef.get() + ", " +
tokenRef.get())));
}
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#JSC2019 @arnaud_bos
private Mono getConnection(long eta, long wait, String
token) {
AtomicLong etaRef = new AtomicLong(eta);
AtomicLong waitRef = new AtomicLong(wait);
AtomicReference tokenRef = new AtomicReference!<>(token);
return Mono.defer(() !-> {
if (etaRef.get() > MAX_ETA_MS) {
return Mono.error(new EtaExceededException());
}
return Mono.delay(Duration.ofMillis(waitRef.get()))
.flatMap(i !-> coordinator.requestConnection(tokenRef.get()));
}).flatMap(c !-> {
if (c instanceof Connection.Available) {
return Mono.just((Connection.Available) c);
} else {
Connection.Unavailable unavail = (Connection.Unavailable) c;
etaRef.set(unavail.getEta());
waitRef.set(unavail.getWait());
tokenRef.set(unavail.getToken());
return Mono.empty();
}
}).repeatWhenEmpty(Repeat
.onlyIf(ctx !-> true)
.doOnRepeat(ctx !->
println(waitRef.get() + ", " + etaRef.get() + ", " +
tokenRef.get())));
}
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#JSC2019 @arnaud_bos
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#JSC2019 @arnaud_bos
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#JSC2019 @arnaud_bos
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#JSC2019 @arnaud_bos
class StateMachineIterator implements Iterator {
private int state;
private int i;
public String next() {
switch(state) {
case 0: state=1; return "A";
case 1: state=2; i=0; return "B";
case 2:
if(i !== 3) state = 3;
return "C" + (i!++);
case 3: state=4; return "D";
case 4: state=5; return "E";
default: throw new NoSuchElementException();
}
}
public boolean hasNext() {
return state < 5;
}
public void remove() {
throw new UnsupportedOperationException("Not supported");
}
}
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#JSC2019 @arnaud_bos
class StateMachineIterator implements Iterator {
private int state;
private int i;
public String next() {
switch(state) {
case 0: state=1; return "A";
case 1: state=2; i=0; return "B";
case 2:
if(i !== 3) state = 3;
return "C" + (i!++);
case 3: state=4; return "D";
case 4: state=5; return "E";
default: throw new NoSuchElementException();
}
}
public boolean hasNext() {
return state < 5;
}
public void remove() {
throw new UnsupportedOperationException("Not supported");
}
}
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#JSC2019 @arnaud_bos
class StateMachineIterator implements Iterator {
private int state;
private int i;
public String next() {
switch(state) {
case 0: state=1; return "A";
case 1: state=2; i=0; return "B";
case 2:
if(i !== 3) state = 3;
return "C" + (i!++);
case 3: state=4; return "D";
case 4: state=5; return "E";
default: throw new NoSuchElementException();
}
}
public boolean hasNext() {
return state < 5;
}
public void remove() {
throw new UnsupportedOperationException("Not supported");
}
}
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#JSC2019 @arnaud_bos
class StateMachineIterator implements Iterator {
private int state;
private int i;
public String next() {
switch(state) {
case 0: state=1; return "A";
case 1: state=2; i=0; return "B";
case 2:
if(i !== 3) state = 3;
return "C" + (i!++);
case 3: state=4; return "D";
case 4: state=5; return "E";
default: throw new NoSuchElementException();
}
}
public boolean hasNext() {
return state < 5;
}
public void remove() {
throw new UnsupportedOperationException("Not supported");
}
}
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#JSC2019 @arnaud_bos
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#JSC2019 @arnaud_bos
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#JSC2019 @arnaud_bos
private Connection.Available getConnection(long eta,
long wait,
String token)
{
for(!;;) {
if (eta > MAX_ETA_MS) {
throw new EtaExceededException();
}
if (wait > 0) {
Thread.sleep(wait);
}
println("Retrying download after " + wait + "ms wait.");
Connection c = coordinator.requestConnection(token);
if (c instanceof Connection.Available) {
return (Connection.Available) c;
}
Connection.Unavailable unavail = (Connection.Unavailable) c;
eta = unavail.getEta();
wait = unavail.getWait();
token = unavail.getToken();
}
}
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#JSC2019 @arnaud_bos
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#JSC2019 @arnaud_bos
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#JSC2019 @arnaud_bos
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#JSC2019 @arnaud_bos
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#JSC2019 @arnaud_bos