Use move strategy to be thread safe for file creation as well

graalvm · Nov 4, 2024 · 97e96e6 · 97e96e6
1 parent 5d84566
commit 97e96e6
Showing 1 changed file with 17 additions and 5 deletions.
diff --git a/common/utils/src/main/java/org/graalvm/buildtools/agent/AgentConfiguration.java b/common/utils/src/main/java/org/graalvm/buildtools/agent/AgentConfiguration.java
@@ -138,26 +138,38 @@ private void addDefaultAccessFilter() {
             return;
         }
 
+        String accessFilterPrefix = "access-filter";
+        String accessFilterSuffix = ".json";
+
         String tempDir = System.getProperty("java.io.tmpdir");
         Path agentDir = Path.of(tempDir).resolve("agent-config");
-        Path accessFilterFile = agentDir.resolve("access-filter.json");
+        Path accessFilterFile = agentDir.resolve(accessFilterPrefix + accessFilterSuffix);
         if (Files.exists(accessFilterFile)) {
             accessFilterFiles.add(accessFilterFile.toString());
             return;
         }
 
-        try(InputStream accessFilter = AgentConfiguration.class.getResourceAsStream(DEFAULT_ACCESS_FILTER_FILE)) {
-            if (accessFilter == null) {
+        try(InputStream accessFilterData = AgentConfiguration.class.getResourceAsStream(DEFAULT_ACCESS_FILTER_FILE)) {
+            if (accessFilterData == null) {
                 throw new IOException("Cannot find access-filter.json on default location: " + DEFAULT_ACCESS_FILTER_FILE);
             }
 
             try {
                 Files.createDirectory(agentDir);
             } catch (FileAlreadyExistsException e) {
-                System.out.println("Agent directory already exists probably because other thread or process created it.");
+                System.out.println("Ignore directory creation because " + agentDir + " directory is already created.");
+            }
+
+            Path tmpAccessFilter = Files.createTempFile(agentDir, accessFilterPrefix, accessFilterSuffix);
+            Files.copy(accessFilterData, tmpAccessFilter);
+
+            try {
+                Files.move(tmpAccessFilter, accessFilterFile, StandardCopyOption.ATOMIC_MOVE);
+            } catch (FileAlreadyExistsException e) {
+                Files.delete(tmpAccessFilter);
+                System.out.println("Access-filter file already exists. Delete temporary one.");
             }
 
-            Files.copy(accessFilter, accessFilterFile, StandardCopyOption.REPLACE_EXISTING);
             accessFilterFiles.add(accessFilterFile.toString());
         } catch (IOException e) {
             throw new RuntimeException("Cannot add default access-filter.json" ,e);