From b8bbd1b015d59523cf2054a6ad42be11dedc8652 Mon Sep 17 00:00:00 2001
From: Ben Culkin <scorpress@gmail.com>
Date: Sun, 25 Jun 2023 16:30:36 -0400
Subject: Add timeout support

Add support for timeouts to Terminal, so you can say you only want to
wait so long for a given reply
---
 .../main/java/bjc/utils/cli/StreamTerminal.java    | 27 ++++++++++++++-
 base/src/main/java/bjc/utils/cli/Terminal.java     | 38 +++++++++++++++++++++-
 2 files changed, 63 insertions(+), 2 deletions(-)

(limited to 'base/src/main/java')

diff --git a/base/src/main/java/bjc/utils/cli/StreamTerminal.java b/base/src/main/java/bjc/utils/cli/StreamTerminal.java
index 69be8d7..87370f8 100644
--- a/base/src/main/java/bjc/utils/cli/StreamTerminal.java
+++ b/base/src/main/java/bjc/utils/cli/StreamTerminal.java
@@ -7,6 +7,8 @@ import java.util.*;
 import java.util.concurrent.*;
 import java.util.concurrent.locks.*;
 
+import bjc.data.Either;
+
 /**
  * Implementation of {@link Terminal} using {@link Reader} and {@link Writer}
  * 
@@ -149,6 +151,24 @@ public class StreamTerminal implements Terminal, Runnable {
 				return pendingReplies.get(id);
 		}
 	}
+	
+	@Override
+	public Optional<String> awaitReply(long id, TimeUnit unit, long delay) throws InterruptedException {
+		if (pendingReplies.containsKey(id))
+			return Optional.of(pendingReplies.get(id));
+		while (true) {
+			replyLock.lock();
+			boolean stat = replyCondition.await(delay, unit);
+			replyLock.unlock();
+			
+			// If we timed out, say so
+			if (stat == false) return Optional.empty();
+			// Explanation: Since the reply map is add-only, the lock isn't actually
+			// protecting anything. We just want to wait until a response is received.
+			if (pendingReplies.containsKey(id))
+				return Optional.of(pendingReplies.get(id));
+		}
+	}
 
 	@Override
 	public Optional<String> checkReply(long id) {
@@ -160,5 +180,10 @@ public class StreamTerminal implements Terminal, Runnable {
 		return awaitReply(submitRequest(req));
 	}
 	
-	// TODO add variants of the two blocking methods above with timeout support
+	@Override
+	public Either<String, Long> submitRequestSync(String req, TimeUnit unit, long delay) throws InterruptedException {
+		long id = submitRequest(req);
+		Optional<String> rep = awaitReply(id, unit, delay);
+		return rep.isEmpty() ? Either.right(id) : Either.left(rep.get());
+	}
 }
\ No newline at end of file
diff --git a/base/src/main/java/bjc/utils/cli/Terminal.java b/base/src/main/java/bjc/utils/cli/Terminal.java
index a10d82e..e8b3029 100644
--- a/base/src/main/java/bjc/utils/cli/Terminal.java
+++ b/base/src/main/java/bjc/utils/cli/Terminal.java
@@ -1,6 +1,9 @@
 package bjc.utils.cli;
 
 import java.util.*;
+import java.util.concurrent.TimeUnit;
+
+import bjc.data.Either;
 
 /**
  * A terminal with support for asking multiple questions, and retrieving the
@@ -17,6 +20,7 @@ public interface Terminal {
 	 * Submit a request to the terminal
 	 * 
 	 * @param req The body of the request
+	 * 
 	 * @return The ID of the request
 	 */
 	long submitRequest(String req);
@@ -26,15 +30,32 @@ public interface Terminal {
 	 * response is available.
 	 * 
 	 * @param id The ID of the request
+	 * 
 	 * @return The response to that request
+	 * 
 	 * @throws InterruptedException If we are interrupted waiting for the reply
 	 */
 	String awaitReply(long id) throws InterruptedException;
+	
+	/**
+	 * Await a reply for a given request. Will block the current thread until a
+	 * response is available or the specified timeout occurs.
+	 * 
+	 * @param id The ID of the request
+	 * @param unit The unit of time to wait
+	 * @param delay The amount of units to wait before timing out
+	 * 
+	 * @return The response to that request, or an empty optional if it timed out
+	 * 
+	 * @throws InterruptedException If we are interrupted waiting for the reply
+	 */
+	Optional<String> awaitReply(long id, TimeUnit unit, long delay) throws InterruptedException;
 
 	/**
 	 * Check if a reply for a request is available, without blocking.
 	 * 
 	 * @param id The ID of the request
+	 * 
 	 * @return The reply to the request if one is available, and empty otherwise
 	 */
 	Optional<String> checkReply(long id);
@@ -47,5 +68,20 @@ public interface Terminal {
 	 * @return The reply to the request
 	 * @throws InterruptedException If we are interrupted waiting for the reply
 	 */
-	String submitRequestSync(String req) throws InterruptedException;;
+	String submitRequestSync(String req) throws InterruptedException;
+
+	/**
+	 * Submit a request and await the reply to it. Will block the current thread
+	 * until a response is received or the timeout occurs.
+	 * 
+	 * @param req The request to submit
+	 * @param unit The unit of time to wait
+	 * @param delay The amount of units to wait before timing out
+	 * 
+	 * @return The reply to the request, or the ID of the request if the timeout occurred
+	 * 
+	 * @throws InterruptedException If we are interrupted waiting for the reply
+	 */
+	Either<String, Long> submitRequestSync(String req, TimeUnit unit, long delay) throws InterruptedException;
+
 }
\ No newline at end of file
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