Import apollo-tracing-js (#1292)

* Initial commit

* 0.0.3

* Replace endOffset with duration in resolver calls

* 0.0.4

* Fix duration

* 0.0.5

* Remove unnecessary schema level resolve function and return schema

* Update README

* 0.0.6

* Update README

* Update dependencies

* 0.0.7

* Update README

* set package.json to point to this repository (#3)

* Update dependencies

Fixes #4.

* 0.0.8

* Add asynciterable support to tsconfig.json

* Skip trace collection when context or context._traceCollector is undefined

Fixes #5.

* 0.0.9

* Rewrite to use graphql-extensions

* 0.0.10

* 0.0.11

* 0.1.0

* Update graphql-extensions dependency and downgrade TS target

* 0.1.1

* Update README

* Update README

* Increase version range for `graphql` peerDependency. (#7)

* 0.1.2

* Update dependencies

* 0.1.3

* [apollo-bot] Update the Issue/PR Templates with auto label (#9)

* Update `graphql` peer dependency range to allow 0.13.x.

* dev: Update TypeScript to latest version, v2.7.2.

* dev: Update jest & dependencies to latest versions.

* dev: Update type definitions for `graphql`, `node` and `jest`.

* Allow `undefined` to return from `format`. (#12)

* Allow `undefined` to return from `format`.

TypeScript 2.7 introduced new "Strict Class Instantiation" rules which,
as the name suggests, require properties which are intended to be set
(eventually, to a type) be set during construction.

Before this change, the `TracingExtension` class was deferred setting these
private properties (namely, `startWallTime`, `endWallTime`, `startHrTime`
and `duration`), but not during instantiation which required setting
marking them as optional and guarding their usage in other methods which
might use those (temporarily `undefined`, if even for a tick) properties.
For example, the expectation that `format` is _only_ called after
`requestDidStart` is not guaranteed with this configuration, even if it is
expected under normal operation.

Therefore, this change adds the additional guarding and updates the `format`
method to return `undefined` in the event that it doesn't have the appropriate
data.

* Update `graphql-extensions` dependency to `~0.0.9`.

Specifically, to take advantage of a type which landed in
`graphql-extensions@0.0.9` thanks to
https://github.com/apollographql/graphql-extensions/pull/10.

* 0.1.4

* Update for graphql-extensions@0.1.0 API (#13)

* Upgrade to TypeScript 2.8

* Add tslint and prettier

* Update for graphql-extensions@0.1.0 API

* 0.2.0-beta.0

* Make work with newest API usage

format() now gets called before the requestDidStart() EndHandler.

* 0.2.0-beta.1

* remove unused files from tracing package

* upgrade packages, fix compilation bugs, and add test

packages/apollo-tracing-js/README.md

@@ -0,0 +1,25 @@
+# Apollo Tracing (for Node.js)
+
+This package is used to collect and expose trace data in the [Apollo Tracing](https://github.com/apollographql/apollo-tracing) format.
+
+It relies on instrumenting a GraphQL schema to collect resolver timings, and exposes trace data for an individual request under `extensions` as part of the GraphQL response.
+
+This data can be consumed by [Apollo Engine](https://www.apollographql.com/engine/) or any other tool to provide visualization and history of field-by-field execution performance.
+
+## Usage
+
+### Apollo Server
+
+Apollo Server includes built-in support for tracing from version 1.1.0 onwards.
+
+The only code change required is to add `tracing: true` to the options passed to the Apollo Server middleware function for your framework of choice. For example, for Express:
+
+```javascript
+app.use('/graphql', bodyParser.json(), graphqlExpress({
+  schema,
+  context: {},
+  tracing: true,
+}));
+```
+
+> If you are using `express-graphql`, we recommend you switch to Apollo Server. Both `express-graphql` and Apollo Server are based on the [`graphql-js`](https://github.com/graphql/graphql-js) reference implementation, and switching should only require changing a few lines of code.