{"_id":"wasm-metering","_rev":"8-f1fc7d40841f113640468fc21e9e3e84","name":"wasm-metering","description":"injects metering into webassembly binaries","dist-tags":{"latest":"0.2.1"},"versions":{"0.0.0":{"name":"wasm-metering","version":"0.0.0","description":"This is a prototype that injects metering into wasm code","main":"index.js","scripts":{"coverage":"istanbul cover ./tests/index.js","coveralls":"npm run coverage && coveralls {\n gasUsed += gas\n if (gasUsed > limit) {\n throw new Error('out of gas!')\n }\n }\n }\n})\n\nconst result = instance.exports.fac(6)\nconsole.log(`result:${result}, gas used ${gasUsed * 1e-4}`) // result:720, gas used 0.4177\n```\n[Source](./example/index.js)\n\n# API\n## meterJSON\n\n[./index.js:104-224](https://github.com/ewasm/wasm-metering/blob/5ab76de89bc07d0abfaa6d0c776c204a752a0d9d/./index.js#L104-L224 \"Source code on GitHub\")\n\nInjects metering into a JSON output of [wasm2json](https://github.com/ewasm/wasm-json-toolkit#wasm2json)\n\n**Parameters**\n\n- `json` **[Object](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object)** the json tobe metered\n- `opts` **[Object](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object)** \n - `opts.costTable` **\\[[Object](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object)]** the cost table to meter with. See these notes about the default. (optional, default `defaultTable`)\n - `opts.moduleStr` **\\[[String](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String)]** the import string for the metering function (optional, default `'metering'`)\n - `opts.fieldStr` **\\[[String](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String)]** the field string for the metering function (optional, default `'usegas'`)\n - `opts.meterType` **\\[[String](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String)]** the register type that is used to meter. Can be `i64`, `i32`, `f64`, `f32` (optional, default `'i64'`)\n\nReturns **[Object](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object)** the metered json\n\n## meterWASM\n\n[./index.js:236-240](https://github.com/ewasm/wasm-metering/blob/5ab76de89bc07d0abfaa6d0c776c204a752a0d9d/./index.js#L236-L240 \"Source code on GitHub\")\n\nInjects metering into a webassembly binary\n\n**Parameters**\n\n- `json` **[Object](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object)** the json tobe metered\n- `opts` **\\[[Object](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object)](default {})** \n - `opts.costTable` **\\[[Object](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object)]** the cost table to meter with. See these notes about the default. (optional, default `defaultTable`)\n - `opts.moduleStr` **\\[[String](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String)]** the import string for the metering function (optional, default `'metering'`)\n - `opts.fieldStr` **\\[[String](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String)]** the field string for the metering function (optional, default `'usegas'`)\n - `opts.meterType` **\\[[String](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String)]** the register type that is used to meter. Can be `i64`, `i32`, `f64`, `f32` (optional, default `'i64'`)\n- `wasm` \n\nReturns **[Buffer](https://nodejs.org/api/buffer.html)** \n\n## costTable\n\nThe costTable option defines the cost of each of the operations.\nCost Tables consist of an object whose keys are sections in a wasm binary. \nFor example\n```\nmodule.exports = {\n 'start': 1,\n 'type': {\n 'params': {\n 'DEFAULT': 1\n },\n 'return_type': {\n 'DEFAULT': 1\n }\n },\n 'import': 1,\n 'code': {\n 'locals': {\n 'DEFAULT': 1\n },\n 'code': {\n 'DEFAULT': 1\n }\n },\n 'memory': (entry) => {\n return entry.maximum * 10\n },\n 'data': 5\n}\n\n```\n\nKeys can either map to a function which will be given that section's entries or\nan integer which will be used as the cost for each entry or an object whose\nkeys are matched against the [JSON representation](https://github.com/ewasm/wasm-json-toolkit) of the code.\nThe default cost table used is from [here](https://github.com/ewasm/design/blob/master/determining_wasm_gas_costs.md)\n\nThe cost table can use a special key 'DEFAULT' that will be used as the cost value for any fields in a section that are not defined.\n\n## Initial Cost\nThe Initial cost for instantation for the module is calculated from all the \nsections other than the code section (which is metered at runtime). This information is\nstored as a [custom section](https://github.com/WebAssembly/design/blob/master/BinaryEncoding.md#name-section)\nthat is inserted directly after the preamble. It uses the the name `initCost` and\nits payload contains the initial cost encoded as an unsigned leb128 interger.\n\n# LICENSE\n[MPL-2.0](https://tldrlegal.com/license/mozilla-public-license-2.0-(mpl-2))\n","maintainers":[{"name":"null_radix","email":"null_radix@riseup.net"}],"time":{"modified":"2022-06-28T21:54:11.175Z","created":"2016-04-13T16:28:45.953Z","0.0.0":"2016-04-13T16:28:45.953Z","0.1.0":"2016-12-22T04:46:17.317Z","0.1.1":"2016-12-23T00:04:44.957Z","0.2.0":"2018-04-05T22:31:17.781Z","0.2.1":"2018-04-06T23:17:54.589Z"},"author":{"name":"mjbecze","email":"mjbecze@gmail.com"},"license":"MPL-2.0","readmeFilename":"README.md","homepage":"https://github.com/ewasm/wasm-metering","keywords":["wasm","metering","webassembly"],"repository":{"type":"git","url":"git+https://github.com/ewasm/wasm-metering.git"},"bugs":{"url":"https://github.com/ewasm/wasm-metering/issues"},"contributors":[{"name":"Alex Beregszaszi","email":"alex@rtfs.hu"}]}