Move TimeUtil into own package and let it have its own java_library

This further reduces the dependencies for the logging/ package as now it
no longer needs to depend on java/com/google/gerrit/common:server, which
is kind of a large package.

The @GwtIncompatible annatation is removed from TimeUtil since this
class is no longer in a package that is shared with GWT.

Change-Id: I9c1c84d2b8feffddb6f8e955035a6a48f9f248c3
Signed-off-by: Edwin Kempin <ekempin@google.com>

java/com/google/gerrit/server/util/time/BUILD

@@ -0,0 +1,9 @@
+java_library(
+    name = "time",
+    srcs = glob(["**/*.java"]),
+    visibility = ["//visibility:public"],
+    deps = [
+        "//lib:guava",
+        "//lib/jgit/org.eclipse.jgit:jgit",
+    ],
+)

java/com/google/gerrit/server/util/time/TimeUtil.java

@@ -0,0 +1,110 @@
+// Copyright (C) 2013 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.server.util.time;
+
+import com.google.common.annotations.VisibleForTesting;
+import java.sql.Timestamp;
+import java.time.Instant;
+import java.util.function.LongSupplier;
+import org.eclipse.jgit.lib.Config;
+import org.eclipse.jgit.storage.file.FileBasedConfig;
+import org.eclipse.jgit.util.FS;
+import org.eclipse.jgit.util.SystemReader;
+
+/** Static utility methods for dealing with dates and times. */
+public class TimeUtil {
+  private static final LongSupplier SYSTEM_CURRENT_MILLIS_SUPPLIER = System::currentTimeMillis;
+
+  private static volatile LongSupplier currentMillisSupplier = SYSTEM_CURRENT_MILLIS_SUPPLIER;
+
+  public static long nowMs() {
+    // We should rather use Instant.now(Clock).toEpochMilli() instead but this would require some
+    // changes in our testing code as we wouldn't have clock steps anymore.
+    return currentMillisSupplier.getAsLong();
+  }
+
+  public static Instant now() {
+    return Instant.ofEpochMilli(nowMs());
+  }
+
+  public static Timestamp nowTs() {
+    return new Timestamp(nowMs());
+  }
+
+  public static Timestamp truncateToSecond(Timestamp t) {
+    return new Timestamp((t.getTime() / 1000) * 1000);
+  }
+
+  @VisibleForTesting
+  public static void setCurrentMillisSupplier(LongSupplier customCurrentMillisSupplier) {
+    currentMillisSupplier = customCurrentMillisSupplier;
+
+    SystemReader oldSystemReader = SystemReader.getInstance();
+    if (!(oldSystemReader instanceof GerritSystemReader)) {
+      SystemReader.setInstance(new GerritSystemReader(oldSystemReader));
+    }
+  }
+
+  @VisibleForTesting
+  public static void resetCurrentMillisSupplier() {
+    currentMillisSupplier = SYSTEM_CURRENT_MILLIS_SUPPLIER;
+    SystemReader.setInstance(null);
+  }
+
+  private static class GerritSystemReader extends SystemReader {
+    SystemReader delegate;
+
+    GerritSystemReader(SystemReader delegate) {
+      this.delegate = delegate;
+    }
+
+    @Override
+    public String getHostname() {
+      return delegate.getHostname();
+    }
+
+    @Override
+    public String getenv(String variable) {
+      return delegate.getenv(variable);
+    }
+
+    @Override
+    public String getProperty(String key) {
+      return delegate.getProperty(key);
+    }
+
+    @Override
+    public FileBasedConfig openUserConfig(Config parent, FS fs) {
+      return delegate.openUserConfig(parent, fs);
+    }
+
+    @Override
+    public FileBasedConfig openSystemConfig(Config parent, FS fs) {
+      return delegate.openSystemConfig(parent, fs);
+    }
+
+    @Override
+    public long getCurrentTime() {
+      return currentMillisSupplier.getAsLong();
+    }
+
+    @Override
+    public int getTimezone(long when) {
+      return delegate.getTimezone(when);
+    }
+  }
+
+  private TimeUtil() {}
+}