log scenario index and name, and transaction index and name

[jeremyandrews]

Fixes #551 by including the following details in the request log:

• scenario_index
• scenario_name
• transaction_index (optional)
• transaction_name (optional)

Adding this information to the request log caused the GooseRequestMetric to grow statistically larger than the other members of the GooseMetric enum. Clippy recommended boxing it because of this:

% cargo clippy
    Checking goose v0.17.1-dev (devel/goose)
warning: large size difference between variants
  --> src/metrics.rs:46:1
   |
46 | / pub enum GooseMetric {
47 | |     Request(GooseRequestMetric),
   | |     --------------------------- the largest variant contains at least 280 bytes
48 | |     Transaction(TransactionMetric),
   | |     ------------------------------ the second-largest variant contains at least 72 bytes
49 | |     Scenario(ScenarioMetric),
50 | | }
   | |_^ the entire enum is at least 280 bytes
   |
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#large_enum_variant
   = note: `#[warn(clippy::large_enum_variant)]` on by default
help: consider boxing the large fields to reduce the total size of the enum
   |
47 |     Request(Box<GooseRequestMetric>),
   |             ~~~~~~~~~~~~~~~~~~~~~~~

warning: `goose` (lib) generated 1 warning
    Finished dev [unoptimized + debuginfo] target(s) in 1.92s

Because transaction_index is optional it is represented as a String in the log instead of as a usize (whereas scenario_index is represented as a usize as it's always guaranteed to be set). If empty, it will show up as "", whereas "0" indicates the first transaction in the scenario.

For example, a snippet from a CSV-formatted request log:

elapsed,scenario_index,scenario_name,transaction_index,transaction_name,raw,name,final_url,redirected,response_time,status_code,success,update,user,error,coordinated_omission_elapsed,user_cadence
1,0,loadtest,0,,"GooseRawRequest { method: Get, url: ""http://127.0.0.1:62805/"", headers: [], body: """" }",/,http://127.0.0.1:62805/,false,2,200,true,false,0,,0,0
3,0,loadtest,1,,"GooseRawRequest { method: Get, url: ""http://127.0.0.1:62805/error"", headers: [], body: """" }",/error,http://127.0.0.1:62805/error,false,0,503,false,false,0,503 Service Unavailable: /error,0,0
4,0,loadtest,0,,"GooseRawRequest { method: Get, url: ""http://127.0.0.1:62805/"", headers: [], body: """" }",/,http://127.0.0.1:62805/,false,0,200,true,false,0,,0,0

Or similarly, a snippet from a JSON-formatted request log:

{"coordinated_omission_elapsed":0,"elapsed":0,"error":"","final_url":"http://127.0.0.1:62811/","name":"/","raw":{"body":"","headers":[],"method":"Get","url":"http://127.0.0.1:62811/"},"redirected":false,"response_time":2,"scenario_index":0,"scenario_name":"loadtest","status_code":200,"success":true,"transaction_index":"0","transaction_name":"","update":false,"user":0,"user_cadence":0}
{"coordinated_omission_elapsed":0,"elapsed":3,"error":"503 Service Unavailable: /error","final_url":"http://127.0.0.1:62811/error","name":"/error","raw":{"body":"","headers":[],"method":"Get","url":"http://127.0.0.1:62811/error"},"redirected":false,"response_time":0,"scenario_index":0,"scenario_name":"loadtest","status_code":503,"success":false,"transaction_index":"1","transaction_name":"","update":false,"user":0,"user_cadence":0}
{"coordinated_omission_elapsed":0,"elapsed":4,"error":"","final_url":"http://127.0.0.1:62811/","name":"/","raw":{"body":"","headers":[],"method":"Get","url":"http://127.0.0.1:62811/"},"redirected":false,"response_time":0,"scenario_index":0,"scenario_name":"loadtest","status_code":200,"success":true,"transaction_index":"0","transaction_name":"","update":false,"user":0,"user_cadence":0}

A raw-formatted request log:

GooseRequestMetric { elapsed: 0, scenario_index: 0, scenario_name: "loadtest", transaction_index: "0", transaction_name: "", raw: GooseRawRequest { method: Get, url: "http://127.0.0.1:62816/", headers: [], body: "" }, name: "/", final_url: "http://127.0.0.1:62816/", redirected: false, response_time: 3, status_code: 200, success: true, update: false, user: 0, error: "", coordinated_omission_elapsed: 0, user_cadence: 0 }
GooseRequestMetric { elapsed: 4, scenario_index: 0, scenario_name: "loadtest", transaction_index: "1", transaction_name: "", raw: GooseRawRequest { method: Get, url: "http://127.0.0.1:62816/error", headers: [], body: "" }, name: "/error", final_url: "http://127.0.0.1:62816/error", redirected: false, response_time: 0, status_code: 503, success: false, update: false, user: 0, error: "503 Service Unavailable: /error", coordinated_omission_elapsed: 0, user_cadence: 0 }
GooseRequestMetric { elapsed: 4, scenario_index: 0, scenario_name: "loadtest", transaction_index: "0", transaction_name: "", raw: GooseRawRequest { method: Get, url: "http://127.0.0.1:62816/", headers: [], body: "" }, name: "/", final_url: "http://127.0.0.1:62816/", redirected: false, response_time: 0, status_code: 200, success: true, update: false, user: 0, error: "", coordinated_omission_elapsed: 0, user_cadence: 0 }

And finally, a pretty-formatted request log:

GooseRequestMetric {
    elapsed: 0,
    scenario_index: 0,
    scenario_name: "loadtest",
    transaction_index: "0",
    transaction_name: "",
    raw: GooseRawRequest {
        method: Get,
        url: "http://127.0.0.1:62808/",
        headers: [],
        body: "",
    },
    name: "/",
    final_url: "http://127.0.0.1:62808/",
    redirected: false,
    response_time: 2,
    status_code: 200,
    success: true,
    update: false,
    user: 0,
    error: "",
    coordinated_omission_elapsed: 0,
    user_cadence: 0,
}
GooseRequestMetric {
    elapsed: 3,
    scenario_index: 0,
    scenario_name: "loadtest",
    transaction_index: "1",
    transaction_name: "",
    raw: GooseRawRequest {
        method: Get,
        url: "http://127.0.0.1:62808/error",
        headers: [],
        body: "",
    },
    name: "/error",
    final_url: "http://127.0.0.1:62808/error",
    redirected: false,
    response_time: 0,
    status_code: 503,
    success: false,
    update: false,
    user: 0,
    error: "503 Service Unavailable: /error",
    coordinated_omission_elapsed: 0,
    user_cadence: 0,
}
GooseRequestMetric {
    elapsed: 4,
    scenario_index: 0,
    scenario_name: "loadtest",
    transaction_index: "0",
    transaction_name: "",
    raw: GooseRawRequest {
        method: Get,
        url: "http://127.0.0.1:62808/",
        headers: [],
        body: "",
    },
    name: "/",
    final_url: "http://127.0.0.1:62808/",
    redirected: false,
    response_time: 0,
    status_code: 200,
    success: true,
    update: false,
    user: 0,
    error: "",
    coordinated_omission_elapsed: 0,
    user_cadence: 0,
}

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[jeremyandrews]

Good catch! I neglected to document this:

% cargo clippy
    Checking goose v0.17.1-dev (devel/goose)
warning: large size difference between variants
  --> src/metrics.rs:46:1
   |
46 | / pub enum GooseMetric {
47 | |     Request(GooseRequestMetric),
   | |     --------------------------- the largest variant contains at least 280 bytes
48 | |     Transaction(TransactionMetric),
   | |     ------------------------------ the second-largest variant contains at least 72 bytes
49 | |     Scenario(ScenarioMetric),
50 | | }
   | |_^ the entire enum is at least 280 bytes
   |
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#large_enum_variant
   = note: `#[warn(clippy::large_enum_variant)]` on by default
help: consider boxing the large fields to reduce the total size of the enum
   |
47 |     Request(Box<GooseRequestMetric>),
   |             ~~~~~~~~~~~~~~~~~~~~~~~

warning: `goose` (lib) generated 1 warning
    Finished dev [unoptimized + debuginfo] target(s) in 1.92s

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One potentially unrelated thing.