[kudu] 01/02: [ranger] clarify error message from subprocess

[al...@apache.org]

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alexey pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/kudu.git

commit 21d25d23fc6d0696592668fa56a02a884458982f
Author: Andrew Wong <aw...@cloudera.com>
AuthorDate: Thu Dec 2 21:32:20 2021 -0800

    [ranger] clarify error message from subprocess
    
    Often times, we'll see error messages like the following:
    
    org.apache.kudu.client.NonRecoverableException: unable to send message: Other end of pipe was closed
      at org.apache.kudu.client.KuduException.transformException(KuduException.java:110)
      at org.apache.kudu.client.KuduClient.joinAndHandleException(KuduClient.java:470)
      at org.apache.kudu.client.KuduClient.openTable(KuduClient.java:288)
      ...
    
    with litle explanation of what pipe was closed, when really, it's always
    the Ranger subprocess pipe. This patch adds that context so it's clear
    to users that their pipe-related issues are Ranger client issues.
    
    I tested this manually by running a Ranger test, killing the Ranger
    client subprocess, and witnessing the following Kudu C++ client error
    message:
    
    End of file: Error creating table db.table on the master: Failed to execute Ranger client subprocess request: unable to send message: Other end of pipe was closed
    
    Change-Id: I4a0fcd899439a822c6239494fedb0895adc046fd
    Reviewed-on: http://gerrit.cloudera.org:8080/18067
    Reviewed-by: Alexey Serbin <as...@cloudera.com>
    Tested-by: Kudu Jenkins
---
 src/kudu/ranger/ranger_client.cc       |  3 ++-
 src/kudu/subprocess/subprocess_proxy.h | 16 +++++++++++-----
 2 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/kudu/ranger/ranger_client.cc b/src/kudu/ranger/ranger_client.cc
index 3d9ffa6..e69ce98 100644
--- a/src/kudu/ranger/ranger_client.cc
+++ b/src/kudu/ranger/ranger_client.cc
@@ -390,7 +390,8 @@ Status RangerClient::Start() {
   const string fifo_path = SubprocessServer::FifoPath(RangerFifoBase());
   vector<string> argv;
   RETURN_NOT_OK(BuildArgv(fifo_path, log_properties_path, &argv));
-  subprocess_.reset(new RangerSubprocess(env_, fifo_path, std::move(argv), metric_entity_));
+  subprocess_.reset(new RangerSubprocess(env_, fifo_path, std::move(argv), metric_entity_,
+                                         "Ranger client subprocess"));
   return subprocess_->Start();
 }
 
diff --git a/src/kudu/subprocess/subprocess_proxy.h b/src/kudu/subprocess/subprocess_proxy.h
index d5a5d1b..37f6687 100644
--- a/src/kudu/subprocess/subprocess_proxy.h
+++ b/src/kudu/subprocess/subprocess_proxy.h
@@ -54,8 +54,10 @@ template<class ReqPB, class RespPB, class MetricsPB>
 class SubprocessProxy {
  public:
   SubprocessProxy(Env* env, const std::string& receiver_file,
-                  std::vector<std::string> argv, const scoped_refptr<MetricEntity>& entity)
-      : server_(new SubprocessServer(env, receiver_file, std::move(argv), MetricsPB(entity))) {}
+                  std::vector<std::string> argv, const scoped_refptr<MetricEntity>& entity,
+                  std::string subprocess_name = "subprocess")
+      : server_(new SubprocessServer(env, receiver_file, std::move(argv), MetricsPB(entity))),
+        subprocess_name_(std::move(subprocess_name)) {}
 
   // Starts the underlying subprocess.
   Status Start() {
@@ -69,14 +71,17 @@ class SubprocessProxy {
     SubprocessRequestPB sreq;
     sreq.mutable_request()->PackFrom(req);
     SubprocessResponsePB sresp;
-    RETURN_NOT_OK(server_->Execute(&sreq, &sresp));
+    RETURN_NOT_OK_PREPEND(server_->Execute(&sreq, &sresp),
+        strings::Substitute("Failed to execute $0 request", subprocess_name_));
     if (!sresp.response().UnpackTo(resp)) {
       LOG(ERROR) << strings::Substitute("unable to unpack response: $0",
                                         pb_util::SecureDebugString(sresp));
-      return Status::Corruption("unable to unpack response");
+      return Status::Corruption(
+          strings::Substitute("unable to unpack $0 response", subprocess_name_));
     }
     if (sresp.has_error()) {
-      return StatusFromPB(sresp.error());
+      return StatusFromPB(sresp.error()).CloneAndPrepend(
+          strings::Substitute("error in $0 response", subprocess_name_));
     }
     return Status::OK();
   }
@@ -87,6 +92,7 @@ class SubprocessProxy {
   }
  private:
   std::unique_ptr<SubprocessServer> server_;
+  const std::string subprocess_name_;
 };
 
 } // namespace subprocess