public void onInsertCompleted() {
        if (isFailed) {
            return;
        }
        sessionCache.cacheAfterFlush(metrics);
    }
In some cases, this callback could be shared by multiple executions, such as SQLExecutor#additionalSQLs.
This flag would make sure, once one of the generated executions is failure, the whole metric would be removed
from the cache, and would not be added back. As those are executed in a batch mode. The sequence is uncertain.
oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/storage/SessionCacheCallback.java