CompletableFuture simplified custom example
Could someone explain the original source of CompletableFuture in simple ways? Particularly what happens in timedGet(long nanos)? This is source code link https://github.com/frohoff/jdk8u-jdk/blob/master/src/share/classes/java/util/concurrent/CompletableFuture.java
How CompletableFuture watches an execution of a thread and times out?
java java.util.concurrent
asked Nov 23 '18 at 9:04
J JJ J
74
add a comment |
Could someone explain the original source of CompletableFuture in simple ways? Particularly what happens in timedGet(long nanos)? This is source code link https://github.com/frohoff/jdk8u-jdk/blob/master/src/share/classes/java/util/concurrent/CompletableFuture.java
How CompletableFuture watches an execution of a thread and times out?
java java.util.concurrent
asked Nov 23 '18 at 9:04
J JJ J
74
1
That is a line majority restrict themselves into. Certain things demand to cross that line and check out things for many other reasons.
– J J
Nov 23 '18 at 9:25
add a comment |
Could someone explain the original source of CompletableFuture in simple ways? Particularly what happens in timedGet(long nanos)? This is source code link https://github.com/frohoff/jdk8u-jdk/blob/master/src/share/classes/java/util/concurrent/CompletableFuture.java
How CompletableFuture watches an execution of a thread and times out?
java java.util.concurrent
asked Nov 23 '18 at 9:04
J JJ J
74
Could someone explain the original source of CompletableFuture in simple ways? Particularly what happens in timedGet(long nanos)? This is source code link https://github.com/frohoff/jdk8u-jdk/blob/master/src/share/classes/java/util/concurrent/CompletableFuture.java
How CompletableFuture watches an execution of a thread and times out?
java java.util.concurrent
java java.util.concurrent
asked Nov 23 '18 at 9:04
J JJ J
74
asked Nov 23 '18 at 9:04
J JJ J
74
asked Nov 23 '18 at 9:04
J JJ J
74
asked Nov 23 '18 at 9:04
J JJ J
74
asked Nov 23 '18 at 9:04
J JJ J
74
74
1
That is a line majority restrict themselves into. Certain things demand to cross that line and check out things for many other reasons.
– J J
Nov 23 '18 at 9:25
add a comment |
1
That is a line majority restrict themselves into. Certain things demand to cross that line and check out things for many other reasons.
– J J
Nov 23 '18 at 9:25
1
1
That is a line majority restrict themselves into. Certain things demand to cross that line and check out things for many other reasons.
– J J
Nov 23 '18 at 9:25
That is a line majority restrict themselves into. Certain things demand to cross that line and check out things for many other reasons.
– J J
Nov 23 '18 at 9:25
add a comment |
1 Answer
1
active
oldest
votes
I won't take upon myself to explain the entire CompletableFuture, as it's about 2K lines long, but I cad definitely explain timedGet()
Note that we're discussing OpenJDK here, OracleJDK is a bit different.
There are some checks before the meaty part and some cleanups after. I'll leave them.
long d = System.nanoTime() + nanos;
// Arguments are interruptible, nanos, deadline
Signaller q = new Signaller(true, nanos, d == 0L ? 1L : d); // avoid 0
boolean queued = false;
// We wait until we get the result
// If it's already there, we simply return it
while ((r = result) == null) {
// So, the result is not there
// If it's the first time we run this loop, or we didn't manage to push signaller on the stacked queued=false
if (!queued)
queued = tryPushStack(q);
// Something interrupted us. It could be either thread interrupt or timeout
else if (q.interruptControl < 0 || q.nanos <= 0L) {
q.thread = null;
cleanStack();
if (q.interruptControl < 0)
return null;
throw new TimeoutException();
}
else if (q.thread != null && result == null) {
try {
// Waits for q, without blocking the thread
ForkJoinPool.managedBlock(q);
} catch (InterruptedException ie) {
q.interruptControl = -1;
}
}
}
answered Nov 23 '18 at 10:03
Alexey SoshinAlexey Soshin
6,8051512
add a comment |
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1 Answer
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oldest
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I won't take upon myself to explain the entire CompletableFuture, as it's about 2K lines long, but I cad definitely explain timedGet()
Note that we're discussing OpenJDK here, OracleJDK is a bit different.
There are some checks before the meaty part and some cleanups after. I'll leave them.
long d = System.nanoTime() + nanos;
// Arguments are interruptible, nanos, deadline
Signaller q = new Signaller(true, nanos, d == 0L ? 1L : d); // avoid 0
boolean queued = false;
// We wait until we get the result
// If it's already there, we simply return it
while ((r = result) == null) {
// So, the result is not there
// If it's the first time we run this loop, or we didn't manage to push signaller on the stacked queued=false
if (!queued)
queued = tryPushStack(q);
// Something interrupted us. It could be either thread interrupt or timeout
else if (q.interruptControl < 0 || q.nanos <= 0L) {
q.thread = null;
cleanStack();
if (q.interruptControl < 0)
return null;
throw new TimeoutException();
}
else if (q.thread != null && result == null) {
try {
// Waits for q, without blocking the thread
ForkJoinPool.managedBlock(q);
} catch (InterruptedException ie) {
q.interruptControl = -1;
}
}
}
answered Nov 23 '18 at 10:03
Alexey SoshinAlexey Soshin
6,8051512
add a comment |
I won't take upon myself to explain the entire CompletableFuture, as it's about 2K lines long, but I cad definitely explain timedGet()
Note that we're discussing OpenJDK here, OracleJDK is a bit different.
There are some checks before the meaty part and some cleanups after. I'll leave them.
long d = System.nanoTime() + nanos;
// Arguments are interruptible, nanos, deadline
Signaller q = new Signaller(true, nanos, d == 0L ? 1L : d); // avoid 0
boolean queued = false;
// We wait until we get the result
// If it's already there, we simply return it
while ((r = result) == null) {
// So, the result is not there
// If it's the first time we run this loop, or we didn't manage to push signaller on the stacked queued=false
if (!queued)
queued = tryPushStack(q);
// Something interrupted us. It could be either thread interrupt or timeout
else if (q.interruptControl < 0 || q.nanos <= 0L) {
q.thread = null;
cleanStack();
if (q.interruptControl < 0)
return null;
throw new TimeoutException();
}
else if (q.thread != null && result == null) {
try {
// Waits for q, without blocking the thread
ForkJoinPool.managedBlock(q);
} catch (InterruptedException ie) {
q.interruptControl = -1;
}
}
}
answered Nov 23 '18 at 10:03
Alexey SoshinAlexey Soshin
6,8051512
add a comment |
I won't take upon myself to explain the entire CompletableFuture, as it's about 2K lines long, but I cad definitely explain timedGet()
Note that we're discussing OpenJDK here, OracleJDK is a bit different.
There are some checks before the meaty part and some cleanups after. I'll leave them.
long d = System.nanoTime() + nanos;
// Arguments are interruptible, nanos, deadline
Signaller q = new Signaller(true, nanos, d == 0L ? 1L : d); // avoid 0
boolean queued = false;
// We wait until we get the result
// If it's already there, we simply return it
while ((r = result) == null) {
// So, the result is not there
// If it's the first time we run this loop, or we didn't manage to push signaller on the stacked queued=false
if (!queued)
queued = tryPushStack(q);
// Something interrupted us. It could be either thread interrupt or timeout
else if (q.interruptControl < 0 || q.nanos <= 0L) {
q.thread = null;
cleanStack();
if (q.interruptControl < 0)
return null;
throw new TimeoutException();
}
else if (q.thread != null && result == null) {
try {
// Waits for q, without blocking the thread
ForkJoinPool.managedBlock(q);
} catch (InterruptedException ie) {
q.interruptControl = -1;
}
}
}
answered Nov 23 '18 at 10:03
Alexey SoshinAlexey Soshin
6,8051512
I won't take upon myself to explain the entire CompletableFuture, as it's about 2K lines long, but I cad definitely explain timedGet()
Note that we're discussing OpenJDK here, OracleJDK is a bit different.
There are some checks before the meaty part and some cleanups after. I'll leave them.
long d = System.nanoTime() + nanos;
// Arguments are interruptible, nanos, deadline
Signaller q = new Signaller(true, nanos, d == 0L ? 1L : d); // avoid 0
boolean queued = false;
// We wait until we get the result
// If it's already there, we simply return it
while ((r = result) == null) {
// So, the result is not there
// If it's the first time we run this loop, or we didn't manage to push signaller on the stacked queued=false
if (!queued)
queued = tryPushStack(q);
// Something interrupted us. It could be either thread interrupt or timeout
else if (q.interruptControl < 0 || q.nanos <= 0L) {
q.thread = null;
cleanStack();
if (q.interruptControl < 0)
return null;
throw new TimeoutException();
}
else if (q.thread != null && result == null) {
try {
// Waits for q, without blocking the thread
ForkJoinPool.managedBlock(q);
} catch (InterruptedException ie) {
q.interruptControl = -1;
}
}
}
answered Nov 23 '18 at 10:03
Alexey SoshinAlexey Soshin
6,8051512
answered Nov 23 '18 at 10:03
Alexey SoshinAlexey Soshin
6,8051512
answered Nov 23 '18 at 10:03
Alexey SoshinAlexey Soshin
6,8051512
answered Nov 23 '18 at 10:03
Alexey SoshinAlexey Soshin
6,8051512
6,8051512
add a comment |
add a comment |
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1
That is a line majority restrict themselves into. Certain things demand to cross that line and check out things for many other reasons.
– J J
Nov 23 '18 at 9:25