envoyproxy/envoy

stats: inconsistent handling of multiple consecutive dots in stat-names produced via join vs direct encoding

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#10,008 opened on Feb 11, 2020

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Description

You can create a multi-segment stat-name by directly encoding it into the table, or by joining multiple existing stat names.

When you encode directly, you can wind up with multiple consecutive dots. When you construct by joining, you can't. The testcase in this commit illustrates the problem:

https://github.com/jmarantz/envoy/commit/6e7367c522c2fb5e77bb1d59cb54817e039bd9c3

TEST_P(StatNameTest, TestIgnoreTrailingDots) {
  EXPECT_EQ("foo.bar", encodeDecode("foo.bar."));
  EXPECT_EQ("foo.bar", encodeDecode("foo.bar..."));
  EXPECT_EQ("foo..bar", encodeDecode("foo..bar"));
  EXPECT_EQ("foo...bar", encodeDecode("foo...bar"));

  StatNamePool pool(*table_);
  SymbolTable::StoragePtr joined = table_->join({makeStat("a"), makeStat(""), makeStat("b")});
  EXPECT_EQ("a..b", table_->toString(StatName(joined.get())));   // FAILS, will be "a.b".

  EXPECT_EQ("", encodeDecode("."));
  EXPECT_EQ("", encodeDecode(".."));
}

Contributor guide

Research direction
Examine the join method and the encoding function to ensure consistent handling of consecutive dots.
Tech stack
None
Domain
backend
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
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++Testing
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
70