[jira] [Resolved] (IMPALA-5327) Handle return value and exception of JNI GetStringUTFChars()

["Tianyi Wang (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/IMPALA-5327?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Tianyi Wang resolved IMPALA-5327.
---------------------------------
       Resolution: Fixed
    Fix Version/s: Impala 2.10.0

IMPALA-5327: Handle return of JNI GetStringUTFChar

GetStringUTFChars may return NULL or throw exception and it is not
handled in two places. This patch checks the return value/exception,
logs if there is error and return error to the caller. A helper class
JniUtfCharGuard is added to jni-util.h/cc to manage the lifetime.

Change-Id: I47eed045f21c6ed3a8decf422ce8429fc66c4322
Reviewed-on: http://gerrit.cloudera.org:8080/7642
Reviewed-by: Tim Armstrong <ta...@cloudera.com>
Tested-by: Impala Public Jenkins

> Handle return value and exception of JNI GetStringUTFChars()
> ------------------------------------------------------------
>
>                 Key: IMPALA-5327
>                 URL: https://issues.apache.org/jira/browse/IMPALA-5327
>             Project: IMPALA
>          Issue Type: Bug
>          Components: Backend
>    Affects Versions: Impala 2.5.0, Impala 2.6.0, Impala 2.7.0, Impala 2.8.0
>            Reporter: Alexander Behm
>            Assignee: Tianyi Wang
>            Priority: Critical
>              Labels: crash, ramp-up
>             Fix For: Impala 2.10.0
>
>
> Several places in the code do not handle JNI GetStringUTFChars() correctly.
> 1. GetStringUTFChars() returns NULL if there is insufficient memory
> 2. GetStringUTFChars() may set an exception in the JNI env. That exception must be checked and clearer before any other call to the JNI env.
> Here's an example of the poor handling from jni-util.cc:
> {code}
> Status JniUtil::GetJniExceptionMsg(JNIEnv* env, bool log_stack, const string& prefix) {
>   jthrowable exc = (env)->ExceptionOccurred();
>   if (exc == NULL) return Status::OK();
>   env->ExceptionClear();
>   DCHECK(throwable_to_string_id() != NULL);
>   jstring msg = (jstring) env->CallStaticObjectMethod(jni_util_class(),
>       throwable_to_string_id(), exc);
>   jboolean is_copy;
>   string error_msg =
>       (reinterpret_cast<const char*>(env->GetStringUTFChars(msg, &is_copy)));
>   if (log_stack) {
>     jstring stack = (jstring) env->CallStaticObjectMethod(jni_util_class(),
>         throwable_to_stack_trace_id(), exc);
>     const char* c_stack =
>       reinterpret_cast<const char*>(env->GetStringUTFChars(stack, &is_copy));
>     VLOG(1) << string(c_stack);
>   }
>   env->ExceptionClear();
>   env->DeleteLocalRef(exc);
>   stringstream ss;
>   ss << prefix << error_msg;
>   return Status(ss.str());
> }
> {code}



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