Rewrite the Command API

Important: the simplified API now defaults to forwarding interrupts to
subprocesses. I did audit all the call sites, and I think this is a safe change
to make.

- Properly support timeouts with all implementations
- Simplify the API
  - only provide two flavours of blocking calls, which require no input and
    forward interrupts; this is the most common usage
  - provide a number of async calls, which optionally takes input, and a flag
    whether to forward interrupts
  - only support input streams, no byte arrays or other 'convenience features'
    that are rarely needed and unnecessarily increase the surface area
  - use java.time.Duration to specify timeout; for consistency, interpret a
    timeout of <= 0 as no timeout (i.e., including rather than excluding 0)
  - KillableObserver and subclasses are no longer part of the public API, but
    still used to implement timeouts if the Subprocess.Factory does not support
    them
- Update the documentation for Command
- Update all callers; most callers now use the simplified API

PiperOrigin-RevId: 164716782

2 files changed, 7 insertions, 1 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/windows/WindowsSubprocess.java b/src/main/java/com/google/devtools/build/lib/windows/WindowsSubprocess.java
index 59d9792696..d99cafe6a7 100644
--- a/src/main/java/com/google/devtools/build/lib/windows/WindowsSubprocess.java
+++ b/src/main/java/com/google/devtools/build/lib/windows/WindowsSubprocess.java
@@ -133,7 +133,8 @@ public class WindowsSubprocess implements Subprocess {
       boolean stderrRedirected, long timeoutMillis) {
     this.commandLine = commandLine;
     this.nativeProcess = nativeProcess;
-    this.timeoutMillis = timeoutMillis;
+    // As per the spec of Command, we should only apply timeouts that are > 0.
+    this.timeoutMillis = timeoutMillis <= 0 ? -1 : timeoutMillis;
     stdoutStream =
         stdoutRedirected ? null : new ProcessInputStream(WindowsProcesses.getStdout(nativeProcess));
     stderrStream =
diff --git a/src/main/java/com/google/devtools/build/lib/windows/WindowsSubprocessFactory.java b/src/main/java/com/google/devtools/build/lib/windows/WindowsSubprocessFactory.java
index e398a3b195..d033bacf13 100644
--- a/src/main/java/com/google/devtools/build/lib/windows/WindowsSubprocessFactory.java
+++ b/src/main/java/com/google/devtools/build/lib/windows/WindowsSubprocessFactory.java
@@ -37,6 +37,11 @@ public class WindowsSubprocessFactory implements Subprocess.Factory {
   }
 
   @Override
+  public boolean supportsTimeout() {
+    return true;
+  }
+
+  @Override
   public Subprocess create(SubprocessBuilder builder) throws IOException {
     List<String> argv = builder.getArgv();