Fault Tolerance SE Documentation (#2399)

* Initial draft.

Signed-off-by: Santiago Pericasgeertsen <santiago.pericasgeertsen@oracle.com>

* New section and fixed some typos.

Signed-off-by: Santiago Pericasgeertsen <santiago.pericasgeertsen@oracle.com>

* Some new sections and a new file name.

Signed-off-by: Santiago Pericasgeertsen <santiago.pericasgeertsen@oracle.com>

* Links to Javadocs.

Signed-off-by: Santiago Pericasgeertsen <santiago.pericasgeertsen@oracle.com>

* Updated sitegen.yaml with new entry for FT.

Signed-off-by: Santiago Pericasgeertsen <santiago.pericasgeertsen@oracle.com>

* Updated sitegen.yaml with new entry for FT.

Signed-off-by: Santiago Pericasgeertsen <santiago.pericasgeertsen@oracle.com>

* Updates to the Handler Composition section with new example. Some minor fixes in Javadocs referenced from this document.

Signed-off-by: Santiago Pericasgeertsen <santiago.pericasgeertsen@oracle.com>

* Some minor rewording in Bulkhead section.

Signed-off-by: Santiago Pericasgeertsen <santiago.pericasgeertsen@oracle.com>

* A couple of more typos.

Signed-off-by: Santiago Pericasgeertsen <santiago.pericasgeertsen@oracle.com>

fault-tolerance/src/main/java/io/helidon/faulttolerance/Bulkhead.java

@@ -125,6 +125,10 @@ public interface Bulkhead extends FtHandler {
         }
     }
 
+    /**
+     * Provides statistics during the lifetime of a bulkhead, such as
+     * concurrent executions, accepted/rejected calls and queue size.
+     */
     interface Stats {
 
         /**

fault-tolerance/src/main/java/io/helidon/faulttolerance/CircuitBreaker.java

@@ -26,7 +26,7 @@ import io.helidon.common.LazyValue;
 
 /**
  * CircuitBreaker protects a potentially failing endpoint from overloading and the application
- * from spending resources on such a failing endpoints.
+ * from spending resources on those endpoints.
  * <p>
  * In case too many errors are detected, the circuit opens and all new requests fail with a
  * {@link io.helidon.faulttolerance.CircuitBreakerOpenException} for a period of time.
@@ -64,7 +64,11 @@ public interface CircuitBreaker extends FtHandler {
     void state(State newState);
 
     /**
-     * {@link io.helidon.faulttolerance.CircuitBreaker} states.
+     * A circuit breaker can be in any of 3 possible states as defined by this enum.
+     * The {@link State#CLOSED} state is the normal one; an {@link State#OPEN} state
+     * indicates the circuit breaker is blocking requests and {@link State#HALF_OPEN}
+     * that a circuit breaker is transitioning to a {@link State#CLOSED} state
+     * provided enough successful requests are observed.
      */
     enum State {
         /**

fault-tolerance/src/main/java/io/helidon/faulttolerance/Fallback.java

@@ -28,7 +28,7 @@ import io.helidon.common.reactive.Multi;
 import io.helidon.common.reactive.Single;
 
 /**
- * Fallback allows the user to execute an alternative supplier of results in case the usual one fails.
+ * Fallback allows the user to execute an alternative function in case the provided supplier fails.
  * <p>
  * In case you call the {@link #invokeMulti(java.util.function.Supplier)} method, the following restriction applies:
  * <ul>

fault-tolerance/src/main/java/io/helidon/faulttolerance/Timeout.java

@@ -22,7 +22,7 @@ import java.util.concurrent.ScheduledExecutorService;
 import io.helidon.common.LazyValue;
 
 /**
- * Timeout attempts to terminate execution after the duration time passes.
+ * Timeout attempts to terminate execution after a duration time passes.
  * In such a case, the consumer of this handler receives a {@link io.helidon.common.reactive.Single}
  * or {@link io.helidon.common.reactive.Multi} with a {@link java.util.concurrent.TimeoutException}.
  */

fault-tolerance/src/main/java/io/helidon/faulttolerance/package-info.java

@@ -15,6 +15,6 @@
  */
 
 /**
- * Fault tolerance for Helidon reactive implementation.
+ * Fault tolerance for Helidon SE reactive implementation.
  */
 package io.helidon.faulttolerance;