fix: version in-memory source snapshots

Author: georgewfraser

src/main/java/org/javacs/Parser.java

@@ -5,7 +5,6 @@
 import com.sun.source.util.*;
 import java.io.IOException;
 import java.nio.file.*;
-import java.time.Instant;
 import java.util.*;
 import java.util.logging.Logger;
 import java.util.regex.Pattern;
@@ -188,7 +187,7 @@ private static int indexOf(CharSequence contents, String name, int start) {
     private static final DocCommentTree EMPTY_DOC = makeEmptyDoc();
 
     private static DocCommentTree makeEmptyDoc() {
-        var file = new SourceFileObject(Paths.get("/Foo.java"), "/** */ class Foo { }", Instant.now());
+        var file = new SourceFileObject(Paths.get("/Foo.java"), "/** */ class Foo { }", SourceFileObject.now());
         var task =
                 (JavacTask)
                         COMPILER.getTask(

src/main/java/org/javacs/SourceFileObject.java

@@ -3,7 +3,7 @@
 import java.io.*;
 import java.net.URI;
 import java.nio.file.Path;
-import java.time.Instant;
+import java.util.concurrent.atomic.AtomicLong;
 import javax.lang.model.element.Modifier;
 import javax.lang.model.element.NestingKind;
 import javax.tools.JavaFileObject;
@@ -13,20 +13,31 @@ public class SourceFileObject implements JavaFileObject {
     final Path path;
     /** contents is the text in this file, or null if we should use the text in FileStore */
     final String contents;
-    /** if contents is set, the modified time of contents */
-    final Instant modified;
+    /** if contents is set, the modified version of contents in monotonic nanoseconds */
+    final long modified;
+    private static final AtomicLong LAST_NOW = new AtomicLong();
 
     public SourceFileObject(Path path) {
-        this(path, null, Instant.EPOCH);
+        this(path, null, 0);
     }
 
-    public SourceFileObject(Path path, String contents, Instant modified) {
+    public SourceFileObject(Path path, String contents, long modified) {
         if (!FileStore.isJavaFile(path)) throw new RuntimeException(path + " is not a java source");
         this.path = path;
         this.contents = contents;
         this.modified = modified;
     }
 
+    public static long now() {
+        while (true) {
+            var previous = LAST_NOW.get();
+            var candidate = Math.max(System.nanoTime(), previous + 1);
+            if (LAST_NOW.compareAndSet(previous, candidate)) {
+                return candidate;
+            }
+        }
+    }
+
     @Override
     public boolean equals(Object other) {
         if (other.getClass() != SourceFileObject.class) return false;
@@ -117,7 +128,7 @@ public Writer openWriter() {
     @Override
     public long getLastModified() {
         if (contents != null) {
-            return modified.toEpochMilli();
+            return modified;
         }
         var fileModified = FileStore.modified(path);
         if (fileModified == null) return 0;

src/main/java/org/javacs/completion/CompletionProvider.java

@@ -145,7 +145,7 @@ private int endOfLine(CharSequence contents, int cursor) {
 
     private CompletionList compileAndComplete(Path file, String contents, long cursor) {
         var started = Instant.now();
-        var source = new SourceFileObject(file, contents, Instant.now());
+        var source = new SourceFileObject(file, contents, SourceFileObject.now());
         var partial = partialIdentifier(contents, (int) cursor);
         var endsWithParen = endsWithParen(contents, (int) cursor);
         try (var task = compiler.compile(List.of(source))) {

src/test/java/org/javacs/BenchmarkParser.java

@@ -4,7 +4,6 @@
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
-import java.time.Instant;
 import java.util.concurrent.TimeUnit;
 import java.util.logging.Logger;
 import org.openjdk.jmh.annotations.*;
@@ -31,7 +30,7 @@ public void setup() throws IOException {
         }
 
         public SourceFileObject source() {
-            return new SourceFileObject(file, contents, Instant.ofEpochMilli(++version));
+            return new SourceFileObject(file, contents, ++version);
         }
 
         private static void quietBenchmarkLogging() {

src/test/java/org/javacs/BenchmarkPruner.java

@@ -3,7 +3,6 @@
 import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Paths;
-import java.time.Instant;
 import java.util.Collections;
 import java.util.List;
 import java.util.Set;
@@ -48,7 +47,7 @@ public SourceFileObject prunedSource() {
         }
 
         private SourceFileObject source(String contents) {
-            return new SourceFileObject(file, contents, Instant.ofEpochMilli(++version));
+            return new SourceFileObject(file, contents, ++version);
         }
 
         private static JavaCompilerService createCompiler() {

src/test/java/org/javacs/CompletionsBase.java

@@ -5,16 +5,10 @@
 import java.util.stream.Stream;
 import org.javacs.lsp.*;
 import org.junit.Assert;
-import org.junit.Before;
 
 public class CompletionsBase {
     protected static JavaLanguageServer server = LanguageServerFixture.getJavaLanguageServer();
 
-    @Before
-    public void resetServer() {
-        refreshServer();
-    }
-
     protected void refreshServer() {
         server = LanguageServerFixture.getJavaLanguageServer();
     }

src/test/java/org/javacs/JavaCompilerServiceTest.java

@@ -1,26 +1,37 @@
 package org.javacs;
 
-import static org.hamcrest.Matchers.*;
-import static org.junit.Assert.*;
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.containsString;
+import static org.hamcrest.Matchers.not;
 
-import java.nio.file.*;
-import java.util.*;
-import org.junit.*;
+import java.util.List;
+import org.junit.Test;
 
 public class JavaCompilerServiceTest {
-    static {
-        Main.setRootFormat();
-    }
-
-    private JavaCompilerService compiler =
-            new JavaCompilerService(Collections.emptySet(), Collections.emptySet(), Collections.emptySet());
+    @Test
+    public void compileDoesNotReuseStaleInMemorySourceForSamePathAndNewVersion() {
+        var compiler = LanguageServerFixture.getCompilerProvider();
+        var file = LanguageServerFixture.DEFAULT_WORKSPACE_ROOT.resolve("src/org/javacs/example/CacheKeyRegression.java");
+        var firstModified = SourceFileObject.now();
+        var secondModified = SourceFileObject.now();
+        var first =
+                new SourceFileObject(
+                        file,
+                        "package org.javacs.example; class CacheKeyRegression { int first; }",
+                        firstModified);
+        var second =
+                new SourceFileObject(
+                        file,
+                        "package org.javacs.example; class CacheKeyRegression { int second; }",
+                        secondModified);
 
-    static Path simpleProjectSrc() {
-        return Paths.get("src/test/examples/simple-project").normalize();
-    }
+        try (var compile = compiler.compile(List.of(first))) {
+            assertThat(compile.root().toString(), containsString("first"));
+        }
 
-    @Before
-    public void setWorkspaceRoot() {
-        FileStore.setWorkspaceRoots(Set.of(simpleProjectSrc()));
+        try (var compile = compiler.compile(List.of(second))) {
+            assertThat(compile.root().toString(), containsString("second"));
+            assertThat(compile.root().toString(), not(containsString("first")));
+        }
     }
 }