Roll forward of https://github.com/bazelbuild/bazel/commit/656a0bab1e025ff3c27d595284a4bf1c5a8d8028 with test (unknown commit) and fix.

Big round of sandbox fixes / performance improvements.

- The number of stat() syscalls in the SymlinkedSandboxedSpawn was way too high. Do less, feel better.

- When using --experimental_sandbox_base, ensure that symlinks in the path are resolved. Before this, you had to check whether on your system /dev/shm is a symlink to /run/shm and then use that instead. Now it no longer matters, as symlinks are resolved.

- Remove an unnecessary directory creation from each sandboxed invocation. Turns out that the "tmpdir" that we created was no longer used after some changes to Bazel's TMPDIR handling.

- Use simpler sandbox paths, by using the unique ID for each Spawn provided by SpawnExecutionPolicy instead of a randomly generated temp folder name. This also saves a round-trip from our VFS to NIO and back. Clean up the sandbox base before each build to ensure that the unique IDs are actually unique. ;)

- Use Java 8's Process#isAlive to check whether a process is alive instead of trying to get the exitcode and catching an exception.

Closes #4913.

PiperOrigin-RevId: 193031017

2 files changed, 4 insertions, 34 deletions

diff --git a/src/test/java/com/google/devtools/build/lib/sandbox/SandboxTestCase.java b/src/test/java/com/google/devtools/build/lib/sandbox/SandboxTestCase.java
index 39f2227af5..8489c7d914 100644
--- a/src/test/java/com/google/devtools/build/lib/sandbox/SandboxTestCase.java
+++ b/src/test/java/com/google/devtools/build/lib/sandbox/SandboxTestCase.java
@@ -15,9 +15,8 @@ package com.google.devtools.build.lib.sandbox;
 
 import com.google.devtools.build.lib.testutil.TestUtils;
 import com.google.devtools.build.lib.vfs.FileSystem;
-import com.google.devtools.build.lib.vfs.FileSystemUtils;
 import com.google.devtools.build.lib.vfs.Path;
-import com.google.devtools.build.lib.vfs.util.FileSystems;
+import com.google.devtools.build.lib.vfs.inmemoryfs.InMemoryFileSystem;
 import org.junit.Before;
 
 /** Common parts of all sandbox tests. */
@@ -27,8 +26,8 @@ public class SandboxTestCase {
 
   @Before
   public final void createTestRoot() throws Exception {
-    fileSystem = FileSystems.getNativeFileSystem();
+    fileSystem = new InMemoryFileSystem();
     testRoot = fileSystem.getPath(TestUtils.tmpDir());
-    FileSystemUtils.deleteTreesBelow(testRoot);
+    testRoot.createDirectoryAndParents();
   }
 }
diff --git a/src/test/java/com/google/devtools/build/lib/sandbox/SymlinkedSandboxedSpawnTest.java b/src/test/java/com/google/devtools/build/lib/sandbox/SymlinkedSandboxedSpawnTest.java
index 5e24deea4a..89fd5eecff 100644
--- a/src/test/java/com/google/devtools/build/lib/sandbox/SymlinkedSandboxedSpawnTest.java
+++ b/src/test/java/com/google/devtools/build/lib/sandbox/SymlinkedSandboxedSpawnTest.java
@@ -58,7 +58,7 @@ public class SymlinkedSandboxedSpawnTest extends SandboxTestCase {
             sandboxDir,
             execRoot,
             ImmutableList.of("/bin/true"),
-            ImmutableMap.<String, String>of(),
+            ImmutableMap.of(),
             ImmutableMap.of(PathFragment.create("such/input.txt"), helloTxt),
             ImmutableSet.of(PathFragment.create("very/output.txt")),
             ImmutableSet.of(execRoot.getRelative("wow/writable")));
@@ -72,35 +72,6 @@ public class SymlinkedSandboxedSpawnTest extends SandboxTestCase {
   }
 
   @Test
-  public void cleanFileSystem() throws Exception {
-    Path helloTxt = workspaceDir.getRelative("hello.txt");
-    FileSystemUtils.createEmptyFile(helloTxt);
-
-    SymlinkedSandboxedSpawn symlinkedExecRoot = new SymlinkedSandboxedSpawn(
-        sandboxDir,
-        execRoot,
-        ImmutableList.of("/bin/true"),
-        ImmutableMap.<String, String>of(),
-        ImmutableMap.of(PathFragment.create("such/input.txt"), helloTxt),
-        ImmutableSet.of(PathFragment.create("very/output.txt")),
-        ImmutableSet.of(execRoot.getRelative("wow/writable")));
-    symlinkedExecRoot.createFileSystem();
-
-    // Pretend to do some work inside the execRoot.
-    execRoot.getRelative("tempdir").createDirectory();
-    FileSystemUtils.createEmptyFile(execRoot.getRelative("very/output.txt"));
-    FileSystemUtils.createEmptyFile(execRoot.getRelative("wow/writable/temp.txt"));
-
-    // Reuse the same execRoot.
-    symlinkedExecRoot.createFileSystem();
-
-    assertThat(execRoot.getRelative("such/input.txt").exists()).isTrue();
-    assertThat(execRoot.getRelative("tempdir").exists()).isFalse();
-    assertThat(execRoot.getRelative("very/output.txt").exists()).isFalse();
-    assertThat(execRoot.getRelative("wow/writable/temp.txt").exists()).isFalse();
-  }
-
-  @Test
   public void copyOutputs() throws Exception {
     // These tests are very simple because we just rely on SandboxedSpawnTest.testMoveOutputs to
     // properly verify all corner cases.