Package com.linecorp.armeria.client.limit

Interface ConcurrencyLimit

Functional Interface:
This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.
@UnstableApi @FunctionalInterface public interface ConcurrencyLimit
Limits the concurrency of client requests.

  • Method Details

    • of

      static ConcurrencyLimit of(int maxConcurrency)
      Returns a newly-created ConcurrencyLimit with the specified maxConcurrency.
      Parameters:
      maxConcurrency - the maximum number of concurrent active requests. Specify 0 to disable the limit.

    • of

      @UnstableApi static ConcurrencyLimit of(IntSupplier maxConcurrency)
      Returns a newly-created ConcurrencyLimit with the specified IntSupplier. IntSupplier.getAsInt() might be frequently called, so please consider using SettableIntSupplier if supplying the value needs heavy computation. For example: 
      
 ConcurrencyLimit limit = ConcurrencyLimit.of(new DynamicLimit());

 class DynamicLimit implements IntSupplier {
     private final SettableIntSupplier settableIntSupplier = SettableIntSupplier.of(16);

     DynamicLimit() {
         LimitChangeListener<Integer> listener = ...
         listener.addListener(updatedValue -> settableIntSupplier.set(updatedValue));
     }

     @Override
     public int getAsInt() {
         return settableIntSupplier.getAsInt();
     }
 }

      Note that IntSupplier must supply a positive number. Otherwise, all requests will end up in pending state.

    • builder

      static ConcurrencyLimitBuilder builder(int maxConcurrency)
      Returns a new ConcurrencyLimitBuilder with the specified maxConcurrency.
      Parameters:
      maxConcurrency - the maximum number of concurrent active requests. Specify 0 to disable the limit.

    • builder

      @UnstableApi static ConcurrencyLimitBuilder builder(IntSupplier maxConcurrency)
      Returns a new ConcurrencyLimitBuilder with the specified IntSupplier. IntSupplier.getAsInt() might be frequently called, so please consider using SettableIntSupplier if supplying the value needs heavy computation. For example: 
      
 ConcurrencyLimitBuilder builder = ConcurrencyLimit.builder(new DynamicLimit());

 class DynamicLimit implements IntSupplier {
     private final SettableIntSupplier settableIntSupplier = SettableIntSupplier.of(16);

     DynamicLimit() {
         LimitChangeListener<Integer> listener = ...
         listener.addListener(updatedValue -> settableIntSupplier.set(updatedValue));
     }

     @Override
     public int getAsInt() {
         return settableIntSupplier.getAsInt();
     }
 }

      Note that IntSupplier must supply a positive number. Otherwise, all requests will end up in pending state.

    • acquire

      CompletableFuture<SafeCloseable> acquire(ClientRequestContext ctx)
      Acquires a SafeCloseable that allows you to execute a job under the limit. The SafeCloseable must be closed after the job is done: 
      
 ConcurrencyLimit limit = ...
 limit.acquire(ctx).handle((permit, cause) -> {
     if (cause != null) {
         // Failed to acquire a permit.
         ...
     }
     // Execute your job.
     ...
     // Release the permit.
     permit.close();
 });