From 361dc79ede2f48586b18cfbbaa0266bc16c058a7 Mon Sep 17 00:00:00 2001
From: CalDescent <caldescent@protonmail.com>
Date: Wed, 22 Dec 2021 19:31:44 +0000
Subject: [PATCH] Fixed bug caused by multiple concurrent builds of the same
 resource.

Several parts of the code request resources to be loaded/built, and these separate threads were tripping over each other and causing build failures. This has been avoided by making sure the resource isn't already building before requesting it.
---
 .../api/gateway/resource/GatewayResource.java |  4 +++-
 .../api/resource/ArbitraryResource.java       | 23 +++++++++++--------
 .../qortal/arbitrary/ArbitraryDataReader.java |  4 ++++
 .../arbitrary/ArbitraryDataRenderer.java      | 21 +++++++++++++++--
 4 files changed, 39 insertions(+), 13 deletions(-)

diff --git a/src/main/java/org/qortal/api/gateway/resource/GatewayResource.java b/src/main/java/org/qortal/api/gateway/resource/GatewayResource.java
index 61aa1aec..0433ec5b 100644
--- a/src/main/java/org/qortal/api/gateway/resource/GatewayResource.java
+++ b/src/main/java/org/qortal/api/gateway/resource/GatewayResource.java
@@ -56,7 +56,9 @@ public class GatewayResource {
         if (build != null && build == true) {
             ArbitraryDataReader reader = new ArbitraryDataReader(name, ArbitraryDataFile.ResourceIdType.NAME, service, null);
             try {
-                reader.loadSynchronously(false);
+                if (!reader.isBuilding()) {
+                    reader.loadSynchronously(false);
+                }
             } catch (Exception e) {
                 // No need to handle exception, as it will be reflected in the status
             }
diff --git a/src/main/java/org/qortal/api/resource/ArbitraryResource.java b/src/main/java/org/qortal/api/resource/ArbitraryResource.java
index 50ee5a68..5825b010 100644
--- a/src/main/java/org/qortal/api/resource/ArbitraryResource.java
+++ b/src/main/java/org/qortal/api/resource/ArbitraryResource.java
@@ -938,17 +938,18 @@ public class ArbitraryResource {
 			// Loop until we have data
 			while (!Controller.isStopping()) {
 				attempts++;
-				try {
-					arbitraryDataReader.loadSynchronously(rebuild);
-					break;
-				} catch (MissingDataException e) {
-					if (attempts > 5) {
-						// Give up after 5 attempts
-						throw ApiExceptionFactory.INSTANCE.createCustomException(request, ApiError.INVALID_CRITERIA, "Data unavailable. Please try again later.");
+				if (!arbitraryDataReader.isBuilding()) {
+					try {
+						arbitraryDataReader.loadSynchronously(rebuild);
+						break;
+					} catch (MissingDataException e) {
+						if (attempts > 5) {
+							// Give up after 5 attempts
+							throw ApiExceptionFactory.INSTANCE.createCustomException(request, ApiError.INVALID_CRITERIA, "Data unavailable. Please try again later.");
+						}
 					}
-
-					Thread.sleep(3000L);
 				}
+				Thread.sleep(3000L);
 			}
 			java.nio.file.Path outputPath = arbitraryDataReader.getFilePath();
 
@@ -986,7 +987,9 @@ public class ArbitraryResource {
 		if (build != null && build == true) {
 			ArbitraryDataReader reader = new ArbitraryDataReader(name, ArbitraryDataFile.ResourceIdType.NAME, service, null);
 			try {
-				reader.loadSynchronously(false);
+				if (!reader.isBuilding()) {
+					reader.loadSynchronously(false);
+				}
 			} catch (Exception e) {
 				// No need to handle exception, as it will be reflected in the status
 			}
diff --git a/src/main/java/org/qortal/arbitrary/ArbitraryDataReader.java b/src/main/java/org/qortal/arbitrary/ArbitraryDataReader.java
index c95224ed..69112ae8 100644
--- a/src/main/java/org/qortal/arbitrary/ArbitraryDataReader.java
+++ b/src/main/java/org/qortal/arbitrary/ArbitraryDataReader.java
@@ -107,6 +107,10 @@ public class ArbitraryDataReader {
         return false;
     }
 
+    public boolean isBuilding() {
+        return ArbitraryDataBuildManager.getInstance().isInBuildQueue(this.createQueueItem());
+    }
+
     private ArbitraryDataBuildQueueItem createQueueItem() {
         return new ArbitraryDataBuildQueueItem(this.resourceId, this.resourceIdType, this.service, this.identifier);
     }
diff --git a/src/main/java/org/qortal/arbitrary/ArbitraryDataRenderer.java b/src/main/java/org/qortal/arbitrary/ArbitraryDataRenderer.java
index 252833af..bc710fe7 100644
--- a/src/main/java/org/qortal/arbitrary/ArbitraryDataRenderer.java
+++ b/src/main/java/org/qortal/arbitrary/ArbitraryDataRenderer.java
@@ -6,7 +6,9 @@ import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.qortal.api.HTMLParser;
 import org.qortal.arbitrary.ArbitraryDataFile.*;
+import org.qortal.arbitrary.exception.MissingDataException;
 import org.qortal.arbitrary.misc.Service;
+import org.qortal.controller.Controller;
 
 import javax.servlet.ServletContext;
 import javax.servlet.http.HttpServletRequest;
@@ -72,8 +74,23 @@ public class ArbitraryDataRenderer {
                     return this.getLoadingResponse(service, resourceId);
                 }
 
-                // Otherwise, hang the request until the build completes
-                arbitraryDataReader.loadSynchronously(false);
+                // Otherwise, loop until we have data
+                int attempts = 0;
+                while (!Controller.isStopping()) {
+                    attempts++;
+                    if (!arbitraryDataReader.isBuilding()) {
+                        try {
+                            arbitraryDataReader.loadSynchronously(false);
+                            break;
+                        } catch (MissingDataException e) {
+                            if (attempts > 5) {
+                                // Give up after 5 attempts
+                                return ArbitraryDataRenderer.getResponse(response, 404, "Data unavailable. Please try again later.");
+                            }
+                        }
+                    }
+                    Thread.sleep(3000L);
+                }
             }
 
         } catch (Exception e) {