Support recursive use of load.properties (#225)

- Recursively load via indirection / via load.properties
- Detects and handles case where the property source is already loaded

Author: rbygrave

avaje-config/src/main/java/io/avaje/config/InitialLoadContext.java

@@ -5,10 +5,7 @@
 
 import java.io.*;
 import java.lang.System.Logger.Level;
-import java.util.ArrayList;
-import java.util.LinkedHashSet;
-import java.util.List;
-import java.util.Set;
+import java.util.*;
 
 /**
  * Manages the underlying map of properties we are gathering.
@@ -28,6 +25,8 @@ final class InitialLoadContext {
   private final Set<String> loadedResources = new LinkedHashSet<>();
   private final List<File> loadedFiles = new ArrayList<>();
   private final CoreExpressionEval exprEval;
+  private final Set<String> loadCheck = new HashSet<>();
+  private int recursiveLoadCount;
 
   InitialLoadContext(ConfigurationLog log, ResourceLoader resourceLoader) {
     this.log = log;
@@ -89,13 +88,15 @@ InputStream resource(String resourcePath, InitialLoader.Source source) {
       is = resourceStream(resourcePath);
       if (is != null) {
         loadedResources.add(source.key(resourcePath));
+        loadCheck.add(resourcePath);
       }
     } else {
       File file = new File(resourcePath);
       if (file.exists()) {
         try {
           is = new FileInputStream(file);
           loadedResources.add(source.key(resourcePath));
+          loadCheck.add(resourcePath);
           loadedFiles.add(file);
         } catch (FileNotFoundException e) {
           throw new UncheckedIOException(e);
@@ -164,4 +165,15 @@ String getAppName() {
     final var appName = map.get("app.name");
     return (appName != null) ? appName.value() : System.getProperty("app.name");
   }
+
+  boolean alreadyLoaded(String fileName) {
+    return !loadCheck.add(fileName);
+  }
+
+  boolean allowRecursiveLoad() {
+    if (recursiveLoadCount++ > 100) {
+      throw new IllegalStateException("Recursive loading exceeded 100. Check your load.properties entries");
+    }
+    return true;
+  }
 }

avaje-config/src/main/java/io/avaje/config/InitialLoader.java

@@ -221,8 +221,14 @@ private void loadViaProfiles(Source source) {
   }
 
   private void loadViaPaths(String paths) {
-    for (String path : splitPaths(paths)) {
-      loadWithExtensionCheck(loadContext.eval(path));
+    for (String rawPath : splitPaths(paths)) {
+      String path = loadContext.eval(rawPath);
+      if (!loadContext.alreadyLoaded(path)) {
+        if (loadWithExtensionCheck(path) && loadContext.allowRecursiveLoad()) {
+          // depth first recursively load via load.properties entry
+          loadViaIndirection();
+        }
+      }
     }
   }
 

avaje-config/src/test/java/io/avaje/config/InitialLoaderTest.java

@@ -138,4 +138,18 @@ void load_withSuppressTestResource() {
       System.clearProperty("suppressTestResource");
     }
   }
+
+  @Test
+  void load_withLoadPropertyChain() {
+    InitialLoader loader = newInitialLoader();
+    loader.loadWithExtensionCheck("test-properties/chain/main.properties");
+    var properties = evalFor(loader.load());
+    assertThat(properties.get("value.main").value()).isEqualTo("main");
+    assertThat(properties.get("value.a").value()).isEqualTo("true");
+    assertThat(properties.get("value.b").value()).isEqualTo("true");
+    assertThat(properties.get("value.c").value()).isEqualTo("true");
+    assertThat(properties.get("value.d").value()).isEqualTo("true");
+    assertThat(properties.get("value.e").value()).isEqualTo("true");
+    assertThat(properties.get("override").value()).isEqualTo("e");
+  }
 }

avaje-config/src/test/resources/test-properties/chain/a.properties

@@ -0,0 +1,3 @@
+value.a=true
+override=a
+load.properties=test-properties/chain/c.properties

avaje-config/src/test/resources/test-properties/chain/b.properties

@@ -0,0 +1,3 @@
+value.b=true
+override=b
+load.properties=test-properties/chain/c.properties

avaje-config/src/test/resources/test-properties/chain/c.properties

@@ -0,0 +1,2 @@
+value.c=true
+override=c

avaje-config/src/test/resources/test-properties/chain/d.properties

@@ -0,0 +1,3 @@
+value.d=true
+override=d
+load.properties=test-properties/chain/c.properties

avaje-config/src/test/resources/test-properties/chain/e.properties

@@ -0,0 +1,3 @@
+value.e=true
+override=e
+load.properties=test-properties/chain/main.properties

avaje-config/src/test/resources/test-properties/chain/main.properties

@@ -0,0 +1,3 @@
+load.properties=test-properties/chain/a.properties test-properties/chain/b.properties, test-properties/chain/d.properties test-properties/chain/e.properties
+value.main=main
+override=main