envoyproxy/envoy

Protecting envoy from stacking events on the same fd

Open

#8,925 opened on Nov 7, 2019

View on GitHub
 (3 comments) (0 reactions) (0 assignees)C++ (5,373 forks)batch import
help wantedtech debt

Repository metrics

Stars
 (27,997 stars)
PR merge metrics
 (Avg merge 8d) (378 merged PRs in 30d)

Description

Description: The way envoy FileEventImpl use libevent is tricky. If two FileEventImpl refer to the same fd, eventually the assigned events are stacked and it's probably hard to recover the intention of each other.

https://github.com/envoyproxy/envoy/pull/8922 is the one I encountered but I believe there are more hidden.

We need to figure out

  1. what is pattern we should follow all over envoy,
  2. how to detect the violation
  3. what are the tools to debug when we suspect there is violation

Contributor guide

Research direction
Analyze the libevent usage in Envoy's FileEventImpl to understand how events can stack on the same fd. Investigate the fix in PR #8922 and propose a general pattern to prevent this. Develop detection methods and debugging tools.
Tech stack
cpp
Domain
backend
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
3-5 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
C++
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
25