Issue nebula-plugins#78 Fixed thread-safety for DependencyLockProvide…

…r, IvyRecommendationProvider, PropertyFileRecommendationProvider

src/main/groovy/netflix/nebula/dependency/recommender/provider/DependencyLockProvider.groovy

@@ -4,7 +4,7 @@ import groovy.json.JsonSlurper
 import org.gradle.api.Project
 
 class DependencyLockProvider extends FileBasedRecommendationProvider {
-    Map<String, String> recommendations
+    volatile Map<String, String> recommendations
 
     DependencyLockProvider() {}
 
@@ -14,20 +14,28 @@ class DependencyLockProvider extends FileBasedRecommendationProvider {
 
     @Override
     String getVersion(String org, String name) throws Exception {
-        if (!recommendations) {
-            input.withCloseable {
-                final locks = new JsonSlurper().parse(it)
-                final isDependencyLock4Format = locks.every {
-                    it.value.every {
-                        it.value instanceof Map
+
+        Map<String, String> tmpResult = recommendations
+
+        if (tmpResult == null) {
+            synchronized (this) {
+                tmpResult = recommendations
+                if (tmpResult == null) {
+                    input.withCloseable {
+                        final locks = new JsonSlurper().parse(it)
+                        final isDependencyLock4Format = locks.every {
+                            it.value.every {
+                                it.value instanceof Map
+                            }
+                        }
+                        tmpResult = (isDependencyLock4Format ? locks.collectEntries { it.value } : locks).collectEntries {
+                            [(it.key): it.value.locked]
+                        }
                     }
-                }
-
-                recommendations = (isDependencyLock4Format ? locks.collectEntries { it.value } : locks).collectEntries {
-                    [(it.key): it.value.locked]
+                    recommendations = tmpResult
                 }
             }
         }
-        recommendations[org + ':' + name]
+        tmpResult[org + ':' + name]
     }
 }

src/main/groovy/netflix/nebula/dependency/recommender/provider/IvyRecommendationProvider.groovy

@@ -3,25 +3,33 @@ package netflix.nebula.dependency.recommender.provider
 import org.gradle.api.Project
 
 class IvyRecommendationProvider extends FileBasedRecommendationProvider {
-    Map<String, String> versionsByCoord
+    volatile Map<String, String> versionsByCoord
 
     IvyRecommendationProvider(Project p) { super(p) }
 
     @Override
     String getVersion(String org, String name) throws Exception {
-        if (versionsByCoord == null) {
-            versionsByCoord = [:]
-            getInput().withCloseable {
-                def ivy = new XmlSlurper().parse(it)
-                ivy.dependencies.dependency.each { d ->
-                    versionsByCoord.put("${[email protected]()}:${[email protected]()}".toString(), "${[email protected]()}")
+
+        Map<String, String> tmpResult = versionsByCoord
+
+        if (tmpResult == null) {
+            synchronized (this) {
+                tmpResult = versionsByCoord
+                if (tmpResult == null) {
+                    tmpResult = [:]
+                    getInput().withCloseable {
+                        def ivy = new XmlSlurper().parse(it)
+                        ivy.dependencies.dependency.each { d ->
+                            tmpResult.put("${[email protected]()}:${[email protected]()}".toString(), "${[email protected]()}")
+                        }
+                    }
+                    versionsByCoord = tmpResult
                 }
             }
         }
-        return versionsByCoord["$org:$name".toString()]
+        return tmpResult["$org:$name".toString()]
     }
 
-    @SuppressWarnings("unchecked")
     @Override
     public InputStreamProvider setModule(Object dependencyNotation) {
         if (dependencyNotation == null)

src/main/groovy/netflix/nebula/dependency/recommender/provider/PropertyFileRecommendationProvider.java

@@ -7,7 +7,8 @@
 import java.util.Properties;
 
 public class PropertyFileRecommendationProvider extends FileBasedRecommendationProvider {
-    private Properties recommendations;
+
+    private volatile Properties recommendations;
 
     private FuzzyVersionResolver fuzzyResolver = new FuzzyVersionResolver() {
         @Override
@@ -31,12 +32,20 @@ public PropertyFileRecommendationProvider(Project project) {
 
     @Override
     public String getVersion(String org, String name) throws Exception {
-        if(recommendations == null) {
-            recommendations = new Properties();
-            try (InputStream inputStream = inputProvider.getInputStream()) {
-                recommendations.load(
-                        new EolCommentFilteringReader(
-                                new ColonFilteringReader(new InputStreamReader(inputStream))));
+
+        Properties tmpResult = recommendations;
+
+        if(tmpResult == null) {
+            synchronized (this) {
+                if (tmpResult == null) {
+                    tmpResult = new Properties();
+                    try (InputStream inputStream = inputProvider.getInputStream()) {
+                        tmpResult.load(
+                                new EolCommentFilteringReader(
+                                        new ColonFilteringReader(new InputStreamReader(inputStream))));
+                    }
+                    recommendations = tmpResult;
+                }
             }
         }
         return fuzzyResolver.versionOf(org + "/" + name);