Start cleaning up after ourselves

drrb · drrb · commit 9e5d2d8a4f14 · 2015-01-09T08:31:25.000+11:00
diff --git a/src/main/java/com/github/drrb/javarust/Greetings.java b/src/main/java/com/github/drrb/javarust/Greetings.java
@@ -107,4 +107,14 @@ interface GreetingSetCallback extends Callback {
 
         void apply(GreetingSet.ByReference greetingSet);
     }
+
+    /**
+     * Free the memory used by a Greeting
+     */
+    void dropGreeting(Greeting greeting);
+
+    /**
+     * Free the memory used by a GreetingSet
+     */
+    void dropGreetingSet(GreetingSet greetingSet);
 }
diff --git a/src/main/rust/com/github/drrb/javarust/lib/greetings.rs b/src/main/rust/com/github/drrb/javarust/lib/greetings.rs
@@ -142,6 +142,18 @@ pub extern fn renderGreetings() -> Box<GreetingSet> {
     }
 }
 
+#[no_mangle]
+pub extern fn dropGreeting(_: Box<Greeting>) {
+    // Do nothing here. Because we own it here (we're using a Box) and we're not returning it, Rust
+    // will assume we don't want it anymore.
+}
+
+#[no_mangle]
+pub extern fn dropGreetingSet(_: Box<GreetingSet>) {
+    // Do nothing here. Because we own it here (we're using a Box) and we're not returning it, Rust
+    // will assume we don't want it anymore.
+}
+
 /// Convert a native string to a Rust string
 fn to_string(pointer: &*const c_char) -> String {
     let slice = unsafe { ffi::c_str_to_bytes(pointer) };
diff --git a/src/test/java/com/github/drrb/javarust/GreetingsTest.java b/src/test/java/com/github/drrb/javarust/GreetingsTest.java
@@ -68,7 +68,12 @@ public void shouldGetAStructFromRustByValue() {
     @Test
     public void shouldGetAStructFromRustByReference() {
         Greeting greeting = library.getGreetingByReference();
+
         assertThat(greeting.text, is("Hello from Rust!"));
+
+        // Free the memory after using it. We need to do this because JNA assumes
+        // that the memory is owned by Rust, so Rust must clean it up.
+        library.dropGreeting(greeting);
     }
 
     @Test
@@ -89,6 +94,7 @@ public void shouldGetListOfStringsFromRustInACallback() {
         List<String> greetingStrings = greetings.stream().map(Greeting::getText).collect(toList());
 
         assertThat(greetingStrings, is(asList("Hello!", "Hello again!")));
+        greetings.stream().forEach((greeting) -> library.dropGreeting(greeting));
     }
 
     @Test
@@ -100,5 +106,6 @@ public void shouldGetAStructFromRustContainingAnArrayOfStructs() {
                 .collect(toList());
 
         assertThat(greetings, is(asList("Hello!", "Hello again!")));
+        library.dropGreetingSet(result);
     }
 }

Original file line number	Diff line number	Diff line change
`@@ -107,4 +107,14 @@ interface GreetingSetCallback extends Callback {`
`107`	`107`
`108`	`108`	`void apply(GreetingSet.ByReference greetingSet);`
`109`	`109`	`}`
	`110`	`+`
	`111`	`+ /**`
	`112`	`+ * Free the memory used by a Greeting`
	`113`	`+ */`
	`114`	`+ void dropGreeting(Greeting greeting);`
	`115`	`+`
	`116`	`+ /**`
	`117`	`+ * Free the memory used by a GreetingSet`
	`118`	`+ */`
	`119`	`+ void dropGreetingSet(GreetingSet greetingSet);`
`110`	`120`	`}`
Original file line number	Diff line number	Diff line change
`@@ -68,7 +68,12 @@ public void shouldGetAStructFromRustByValue() {`
`68`	`68`	`@Test`
`69`	`69`	`public void shouldGetAStructFromRustByReference() {`
`70`	`70`	`Greeting greeting = library.getGreetingByReference();`
	`71`	`+`
`71`	`72`	`assertThat(greeting.text, is("Hello from Rust!"));`
	`73`	`+`
	`74`	`+ // Free the memory after using it. We need to do this because JNA assumes`
	`75`	`+ // that the memory is owned by Rust, so Rust must clean it up.`
	`76`	`+ library.dropGreeting(greeting);`
`72`	`77`	`}`
`73`	`78`
`74`	`79`	`@Test`
`@@ -89,6 +94,7 @@ public void shouldGetListOfStringsFromRustInACallback() {`
`89`	`94`	`List<String> greetingStrings = greetings.stream().map(Greeting::getText).collect(toList());`
`90`	`95`
`91`	`96`	`assertThat(greetingStrings, is(asList("Hello!", "Hello again!")));`
	`97`	`+ greetings.stream().forEach((greeting) -> library.dropGreeting(greeting));`
`92`	`98`	`}`
`93`	`99`
`94`	`100`	`@Test`
`@@ -100,5 +106,6 @@ public void shouldGetAStructFromRustContainingAnArrayOfStructs() {`
`100`	`106`	`.collect(toList());`
`101`	`107`
`102`	`108`	`assertThat(greetings, is(asList("Hello!", "Hello again!")));`
	`109`	`+ library.dropGreetingSet(result);`
`103`	`110`	`}`
`104`	`111`	`}`