[Performance] no-cycle: dont scc for each linted file

[soryy708]

I noticed that no-cycle has a cache miss on SCC very often,
turns out that each linted file builds its own SCC, which is unnecessary.
Lets speed things up, by using the already cached SCC, as long as the context is similar (excluding linted file path)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.37%. Comparing base (5c9757c) to head (d0e4752).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3068      +/-   ##
==========================================
+ Coverage   92.21%   94.37%   +2.16%     
==========================================
  Files          82       82              
  Lines        3557     3558       +1     
  Branches     1244     1243       -1     
==========================================
+ Hits         3280     3358      +78     
+ Misses        277      200      -77     

Flag	Coverage Δ
	94.37% <100.00%> (+2.16%)	⬆️

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[soryy708]

I ran this vs master on a large project and measured:

Without this change (v2.30.0): 139 seconds to lint just no-cycle
With this change: 85 seconds to lint just no-cycle
Impact: 38% decrease in lint time

[soryy708]

Pushed a fix for false cache hit for when ExportMap of previous SCC run didn't contain the current file, resulting in us getting a partial SCC from cache.

I ran this vs master on a large project and measured:

Without this change (v2.30.0): 139 seconds to lint just no-cycle
With this change: 94 seconds to lint just no-cycle
Impact: 32% decrease in lint time

Still good IMO

[ljharb]

This looks good, assuming that there's nothing else in the context that might necessitate a fresh scc, including with all the parsers we support. Can you confirm?

[soryy708]

@ljharb in Discord you asked me:

Are we're sure that those are the only 3 keys in context that matter?

You also said

We support eslint 2 - 8, so it'd be good to check the older ones too.

Ok, I logged the context object in StronglyConnectedComponentsBuilder.for, in various ESLint versions. Here are my observations:

ESLint 7.25.0:

{
  "cacheKey": "/path-to-somewhere/node_modules/@typescript-eslint/parser/dist/index.jsd9da56ee23e751184e57ead488db4381bbe0f9fdc987aa0e7c39a448ea5986827e67ce99a36f4c88b10f0e80d55b71bae8fe96ab1747797f208639408c00c378/path-to-somewhere/src/main.ts",
  "settings": {
    "import/extensions": [
      ".ts",
      ".cts",
      ".mts",
      ".tsx",
      ".js",
      ".jsx",
      ".mjs",
      ".cjs"
    ],
    "import/external-module-folders": [
      "node_modules",
      "node_modules/@types"
    ],
    "import/parsers": {
      "@typescript-eslint/parser": [
        ".ts",
        ".cts",
        ".mts",
        ".tsx"
      ]
    },
    "import/resolver": {
      "node": {
        "extensions": [
          ".ts",
          ".cts",
          ".mts",
          ".tsx",
          ".js",
          ".jsx",
          ".mjs",
          ".cjs"
        ]
      }
    }
  },
  "parserOptions": {
    "ecmaFeatures": {
      "globalReturn": false
    },
    "project": "tsconfig.json",
    "sourceType": "module"
  },
  "parserPath": "/path-to-somewhere/node_modules/@typescript-eslint/parser/dist/index.js",
  "path": "/path-to-somewhere/src/main.ts"
}

ESLint 6.8.0:

{
  "cacheKey": "/path-to-somewhere/node_modules/@typescript-eslint/parser/dist/index.jsd9da56ee23e751184e57ead488db4381bbe0f9fdc987aa0e7c39a448ea5986827e67ce99a36f4c88b10f0e80d55b71bae8fe96ab1747797f208639408c00c378/path-to-somewhere/src/main.ts",
  "settings": {
    "import/extensions": [
      ".ts",
      ".cts",
      ".mts",
      ".tsx",
      ".js",
      ".jsx",
      ".mjs",
      ".cjs"
    ],
    "import/external-module-folders": [
      "node_modules",
      "node_modules/@types"
    ],
    "import/parsers": {
      "@typescript-eslint/parser": [
        ".ts",
        ".cts",
        ".mts",
        ".tsx"
      ]
    },
    "import/resolver": {
      "node": {
        "extensions": [
          ".ts",
          ".cts",
          ".mts",
          ".tsx",
          ".js",
          ".jsx",
          ".mjs",
          ".cjs"
        ]
      }
    }
  },
  "parserOptions": {
    "ecmaFeatures": {
      "globalReturn": false
    },
    "project": "tsconfig.json",
    "sourceType": "module"
  },
  "parserPath": "/path-to-somewhere/node_modules/@typescript-eslint/parser/dist/index.js",
  "path": "/path-to-somewhere/src/main.ts"
}

ESLint 5.16.0:

{
  "cacheKey": "/path-to-somewhere/node_modules/@typescript-eslint/parser/dist/index.jsd579e5a92f2fb830c4066e8075b30bdff66e6bb3eafbbfe9dc70dc8ec7c603f47e67ce99a36f4c88b10f0e80d55b71bae8fe96ab1747797f208639408c00c378/path-to-somewhere/src/main.ts",
  "settings": {
    "import/extensions": [
      ".ts",
      ".cts",
      ".mts",
      ".tsx",
      ".js",
      ".jsx",
      ".mjs",
      ".cjs"
    ],
    "import/external-module-folders": [
      "node_modules",
      "node_modules/@types"
    ],
    "import/parsers": {
      "@typescript-eslint/parser": [
        ".ts",
        ".cts",
        ".mts",
        ".tsx"
      ]
    },
    "import/resolver": {
      "node": {
        "extensions": [
          ".ts",
          ".cts",
          ".mts",
          ".tsx",
          ".js",
          ".jsx",
          ".mjs",
          ".cjs"
        ]
      }
    }
  },
  "parserOptions": {
    "ecmaFeatures": {
      "globalReturn": false
    },
    "project": "tsconfig.json",
    "sourceType": "module",
    "ecmaVersion": 6
  },
  "parserPath": "/path-to-somewhere/node_modules/@typescript-eslint/parser/dist/index.js",
  "path": "/path-to-somewhere/src/main.ts"
}

ESLint 4.19.1:

{
  "cacheKey": "/path-to-somewhere/node_modules/@typescript-eslint/parser/dist/index.jsd579e5a92f2fb830c4066e8075b30bdff66e6bb3eafbbfe9dc70dc8ec7c603f47e67ce99a36f4c88b10f0e80d55b71bae8fe96ab1747797f208639408c00c378/path-to-somewhere/src/main.ts",
  "settings": {
    "import/extensions": [
      ".ts",
      ".cts",
      ".mts",
      ".tsx",
      ".js",
      ".jsx",
      ".mjs",
      ".cjs"
    ],
    "import/external-module-folders": [
      "node_modules",
      "node_modules/@types"
    ],
    "import/parsers": {
      "@typescript-eslint/parser": [
        ".ts",
        ".cts",
        ".mts",
        ".tsx"
      ]
    },
    "import/resolver": {
      "node": {
        "extensions": [
          ".ts",
          ".cts",
          ".mts",
          ".tsx",
          ".js",
          ".jsx",
          ".mjs",
          ".cjs"
        ]
      }
    }
  },
  "parserOptions": {
    "ecmaFeatures": {
      "globalReturn": false
    },
    "project": "tsconfig.json",
    "sourceType": "module",
    "ecmaVersion": 6
  },
  "parserPath": "/path-to-somewhere/node_modules/@typescript-eslint/parser/dist/index.js",
  "path": "/path-to-somewhere/src/main.ts"
}

ESLint 3.19.0:

{
  "cacheKey": "/path-to-somewhere/node_modules/@typescript-eslint/parser/dist/index.jsd579e5a92f2fb830c4066e8075b30bdff66e6bb3eafbbfe9dc70dc8ec7c603f47e67ce99a36f4c88b10f0e80d55b71bae8fe96ab1747797f208639408c00c378/path-to-somewhere/src/main.ts",
  "settings": {
    "import/extensions": [
      ".ts",
      ".cts",
      ".mts",
      ".tsx",
      ".js",
      ".jsx",
      ".mjs",
      ".cjs"
    ],
    "import/external-module-folders": [
      "node_modules",
      "node_modules/@types"
    ],
    "import/parsers": {
      "@typescript-eslint/parser": [
        ".ts",
        ".cts",
        ".mts",
        ".tsx"
      ]
    },
    "import/resolver": {
      "node": {
        "extensions": [
          ".ts",
          ".cts",
          ".mts",
          ".tsx",
          ".js",
          ".jsx",
          ".mjs",
          ".cjs"
        ]
      }
    }
  },
  "parserOptions": {
    "ecmaFeatures": {
      "globalReturn": false
    },
    "project": "tsconfig.json",
    "sourceType": "module",
    "ecmaVersion": 6
  },
  "parserPath": "/path-to-somewhere/node_modules/@typescript-eslint/parser/dist/index.js",
  "path": "/path-to-somewhere/src/main.ts"
}

For ESLint 2 I got:

  0:0  error  Parsing error: "parserOptions.project" has been set for @typescript-eslint/parser.
The file does not match your project config: estree.ts.
The file must be included in at least one of the projects provided

In summary, I believe that yes that's all that interests us in the context object, in various supported ESLint versions.