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https://www.maxpixel.net/Post-Impressionist-Post-Impressionism-Fine-Art-Dutch-1428139
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?
computer (n.)
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1640s, "one who calculates, a reckoner, one whose occupation is to make arithmetical calculations,"
computer (n.)
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https://commons.wikimedia.org/wiki/File:Women_holding_parts_of_the_first_four_Army_computers.jpg
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https://www.computerhistory.org/revolution/punched-cards/2/211/2253
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https://youtu.be/Q07PhW5sCEk
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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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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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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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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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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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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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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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public static InputStream blockingRequest(String url, String headers)
throws IOException
{
URL uri = new URL(url);
SocketAddress serverAddress = new InetSocketAddress(uri.getHost(), uri.getPort()
SocketChannel channel = SocketChannel.open(serverAddress);
ByteBuffer buffer = ByteBuffer.wrap((headers + "Host: " + uri.getHost() + "\r\n\
do {
channel.write(buffer);
} while(buffer.hasRemaining());
return channel.socket().getInputStream();
}
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https://blog.paralleluniverse.co/2014/02/04/littles-law/
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private void getConnection(long eta,
long wait,
String token,
CompletionHandler handler)
{
if (eta > MAX_ETA_MS) {
if (handler!=null) handler.failed(new EtaExceededException());
}
boundedServiceExecutor.schedule(() -> {
println("Retrying download after " + wait + "ms wait.");
coordinator.requestConnection(token,
new CompletionHandler<>() {
@Override
public void completed(Connection c) {
if (c instanceof Connection.Available) {
if (handler!=null) handler.completed((Connection.Available) c);
} else {
Connection.Unavailable unavail = (Connection.Unavailable) c;
getConnection(
unavail.getEta(),
unavail.getWait(),
unavail.getToken(),
handler);
}
}
@Override
public void failed(Throwable t) {
...
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private void getConnection(long eta,
long wait,
String token,
CompletionHandler handler)
{
if (eta > MAX_ETA_MS) {
if (handler!=null) handler.failed(new EtaExceededException());
}
boundedServiceExecutor.schedule(() -> {
println("Retrying download after " + wait + "ms wait.");
coordinator.requestConnection(token,
new CompletionHandler<>() {
@Override
public void completed(Connection c) {
if (c instanceof Connection.Available) {
if (handler!=null) handler.completed((Connection.Available) c);
} else {
Connection.Unavailable unavail = (Connection.Unavailable) c;
getConnection(
unavail.getEta(),
unavail.getWait(),
unavail.getToken(),
handler);
}
}
@Override
public void failed(Throwable t) {
...
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private void getConnection(long eta,
long wait,
String token,
CompletionHandler handler)
{
if (eta > MAX_ETA_MS) {
if (handler!=null) handler.failed(new EtaExceededException());
}
boundedServiceExecutor.schedule(() -> {
println("Retrying download after " + wait + "ms wait.");
coordinator.requestConnection(token,
new CompletionHandler<>() {
@Override
public void completed(Connection c) {
if (c instanceof Connection.Available) {
if (handler!=null) handler.completed((Connection.Available) c);
} else {
Connection.Unavailable unavail = (Connection.Unavailable) c;
getConnection(
unavail.getEta(),
unavail.getWait(),
unavail.getToken(),
handler);
}
}
@Override
public void failed(Throwable t) {
...
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private void getConnection(long eta,
long wait,
String token,
CompletionHandler handler)
{
if (eta > MAX_ETA_MS) {
if (handler!=null) handler.failed(new EtaExceededException());
}
boundedServiceExecutor.schedule(() -> {
println("Retrying download after " + wait + "ms wait.");
coordinator.requestConnection(token,
new CompletionHandler<>() {
@Override
public void completed(Connection c) {
if (c instanceof Connection.Available) {
if (handler!=null) handler.completed((Connection.Available) c);
} else {
Connection.Unavailable unavail = (Connection.Unavailable) c;
getConnection(
unavail.getEta(),
unavail.getWait(),
unavail.getToken(),
handler);
}
}
@Override
public void failed(Throwable t) {
...
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private void getConnection(long eta,
long wait,
String token,
CompletionHandler handler)
{
if (eta > MAX_ETA_MS) {
if (handler!=null) handler.failed(new EtaExceededException());
}
boundedServiceExecutor.schedule(() -> {
println("Retrying download after " + wait + "ms wait.");
coordinator.requestConnection(token,
new CompletionHandler<>() {
@Override
public void completed(Connection c) {
if (c instanceof Connection.Available) {
if (handler!=null) handler.completed((Connection.Available) c);
} else {
Connection.Unavailable unavail = (Connection.Unavailable) c;
getConnection(
unavail.getEta(),
unavail.getWait(),
unavail.getToken(),
handler);
}
}
@Override
public void failed(Throwable t) {
...
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public static InputStream blockingRequest(String url, String headers)
throws IOException
{
URL uri = new URL(url);
SocketAddress serverAddress = new InetSocketAddress(uri.getHost(), uri.getPort()
SocketChannel channel = SocketChannel.open(serverAddress);
ByteBuffer buffer = ByteBuffer.wrap((headers + "Host: " + uri.getHost() + "\r\n\
do {
channel.write(buffer);
} while(buffer.hasRemaining());
return channel.socket().getInputStream();
}
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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.getHost()));
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 CompletionHandler<>() {
@Override
public void completed(Integer read,
ByteBuffer attachment) {
// More
// this
// way
// ==>
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https://medium.com/@copyconstruct/the-method-to-epolls-madness-d9d2d6378642
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Flux.interval(Duration.ofSeconds(2L))
.flatMap(l -> coordinator.heartbeat(conn.getToken()))
.doOnNext(c -> println("Pulse!"))
.then()
.doOnTerminate(() -> println("Pulse terminated"));
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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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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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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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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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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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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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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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Connection.Available conn = getConnection();
Runnable pulse = makePulse(conn);
Fiber f = null;
try (InputStream content = gateway.downloadThingy()) {
f = FiberScope.background().schedule(pulse);
ignoreContent(content);
} catch (IOException e) {
err("Download failed.");
throw e;
}
finally {
if (f!=null) {
f.cancel();
}
}
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http://250bpm.com/blog:71
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http://250bpm.com/blog:71
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Connection.Available conn = getConnection();
Runnable pulse = makePulse(conn);
Fiber f = null;
try (InputStream content = gateway.downloadThingy()) {
f = FiberScope.background().schedule(pulse);
ignoreContent(content);
} catch (IOException e) {
err("Download failed.");
throw e;
} finally {
if (f!=null) {
f.cancel();
}
}
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try (FiberScope scope =
FiberScope.open(CANCEL_AT_CLOSE, PROPAGATE_CANCEL))
{
var conn = getConnection();
try (InputStream content = gateway.downloadThingy()) {
Runnable pulse = makePulse(conn, i);
scope.schedule(pulse);
ignoreContent(content);
}
} catch (IOException e) {
err("Download failed.");
throw e;
}
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Papers and Webpages
Flynn, Michael J. - Some Computer Organizations and Their Effectiveness
Haynes, Christopher T. - Logic Continuations
Wand, Mitchell - Continuation-based Multiprocessing
Loitsch, Florian - Exceptional Continuations in JavaScript
Long, James - What's In A Continuation
Reynolds, John C. - The Discoveries of Continuations
Clinger, Hartheimer, Ost - Implementation Strategies for Continuations
Haynes, Friedman, Wand - Obtaining Coroutines with Continuations
Pressler, Ron - Why Continuations are Coming to Java
Repos
https://github.com/forax/loom-fiber/
https://bitbucket.org/arnaudbos/untangled/
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