refactor: convert dag API to async/await (#2664)

* refactor: convert dag API to async/await

* refactor: pull out repeated name to codec conversion code

Author: Alan Shaw

src/cli/commands/dag/resolve.js

@@ -19,10 +19,9 @@ module.exports = {
       const options = {}
 
       try {
-        const result = await ipfs.dag.resolve(ref, options)
         let lastCid
 
-        for (const res of result) {
+        for await (const res of ipfs.dag.resolve(ref, options)) {
           if (CID.isCID(res.value)) {
             lastCid = res.value
           }

src/core/components/dag.js

@@ -0,0 +1,34 @@
+'use strict'
+
+const { parseArgs } = require('./utils')
+
+module.exports = ({ ipld, preload }) => {
+  return async function get (cid, path, options) {
+    [cid, path, options] = parseArgs(cid, path, options)
+
+    if (options.preload !== false) {
+      preload(cid)
+    }
+
+    if (path == null || path === '/') {
+      const value = await ipld.get(cid)
+
+      return {
+        value,
+        remainderPath: ''
+      }
+    } else {
+      let result
+
+      for await (const entry of ipld.resolve(cid, path)) {
+        if (options.localResolve) {
+          return entry
+        }
+
+        result = entry
+      }
+
+      return result
+    }
+  }
+}

src/core/components/dag/get.js

@@ -0,0 +1,70 @@
+'use strict'
+
+const multicodec = require('multicodec')
+const nameToCodec = name => multicodec[name.toUpperCase().replace(/-/g, '_')]
+
+module.exports = ({ ipld, pin, gcLock, preload }) => {
+  return async function put (dagNode, options) {
+    options = options || {}
+
+    if (options.cid && (options.format || options.hashAlg)) {
+      throw new Error('Can\'t put dag node. Please provide either `cid` OR `format` and `hashAlg` options.')
+    } else if (((options.format && !options.hashAlg) || (!options.format && options.hashAlg))) {
+      throw new Error('Can\'t put dag node. Please provide `format` AND `hashAlg` options.')
+    }
+
+    const optionDefaults = {
+      format: multicodec.DAG_CBOR,
+      hashAlg: multicodec.SHA2_256
+    }
+
+    // The IPLD expects the format and hashAlg as constants
+    if (options.format && typeof options.format === 'string') {
+      options.format = nameToCodec(options.format)
+    }
+    if (options.hashAlg && typeof options.hashAlg === 'string') {
+      options.hashAlg = nameToCodec(options.hashAlg)
+    }
+
+    options = options.cid ? options : Object.assign({}, optionDefaults, options)
+
+    // js-ipld defaults to verion 1 CIDs. Hence set version 0 explicitly for
+    // dag-pb nodes
+    if (options.version === undefined) {
+      if (options.format === multicodec.DAG_PB && options.hashAlg === multicodec.SHA2_256) {
+        options.version = 0
+      } else {
+        options.version = 1
+      }
+    }
+
+    let release
+
+    if (options.pin) {
+      release = await gcLock.readLock()
+    }
+
+    try {
+      const cid = await ipld.put(dagNode, options.format, {
+        hashAlg: options.hashAlg,
+        cidVersion: options.version
+      })
+
+      if (options.pin) {
+        await pin.add(cid, {
+          lock: false
+        })
+      }
+
+      if (options.preload !== false) {
+        preload(cid)
+      }
+
+      return cid
+    } finally {
+      if (release) {
+        release()
+      }
+    }
+  }
+}

src/core/components/dag/put.js

@@ -0,0 +1,15 @@
+'use strict'
+
+const { parseArgs } = require('./utils')
+
+module.exports = ({ ipld, preload }) => {
+  return async function * resolve (cid, path, options) { // eslint-disable-line require-await
+    [cid, path, options] = parseArgs(cid, path, options)
+
+    if (options.preload !== false) {
+      preload(cid)
+    }
+
+    yield * ipld.resolve(cid, path)
+  }
+}

src/core/components/dag/resolve.js

@@ -0,0 +1,15 @@
+'use strict'
+
+const { parseArgs } = require('./utils')
+
+module.exports = ({ ipld, preload }) => {
+  return async function * tree (cid, path, options) { // eslint-disable-line require-await
+    [cid, path, options] = parseArgs(cid, path, options)
+
+    if (options.preload !== false) {
+      preload(cid)
+    }
+
+    yield * ipld.tree(cid, path, options)
+  }
+}

src/core/components/dag/tree.js

@@ -0,0 +1,48 @@
+'use strict'
+
+const CID = require('cids')
+const errCode = require('err-code')
+
+exports.parseArgs = (cid, path, options) => {
+  options = options || {}
+
+  // Allow options in path position
+  if (path !== undefined && typeof path !== 'string') {
+    options = path
+    path = undefined
+  }
+
+  if (typeof cid === 'string') {
+    if (cid.startsWith('/ipfs/')) {
+      cid = cid.substring(6)
+    }
+
+    const split = cid.split('/')
+
+    try {
+      cid = new CID(split[0])
+    } catch (err) {
+      throw errCode(err, 'ERR_INVALID_CID')
+    }
+
+    split.shift()
+
+    if (split.length > 0) {
+      path = split.join('/')
+    } else {
+      path = path || '/'
+    }
+  } else if (Buffer.isBuffer(cid)) {
+    try {
+      cid = new CID(cid)
+    } catch (err) {
+      throw errCode(err, 'ERR_INVALID_CID')
+    }
+  }
+
+  return [
+    cid,
+    path,
+    options
+  ]
+}

src/core/components/dag/utils.js

@@ -8,6 +8,12 @@ exports.block = {
   stat: require('./block/stat')
 }
 exports.config = require('./config')
+exports.dag = {
+  get: require('./dag/get'),
+  put: require('./dag/put'),
+  resolve: require('./dag/resolve'),
+  tree: require('./dag/tree')
+}
 exports.init = require('./init')
 exports.pin = {
   add: require('./pin/add'),
@@ -18,7 +24,6 @@ exports.start = require('./start')
 exports.stop = require('./stop')
 
 exports.legacy = { // TODO: these will be removed as the new API is completed
-  dag: require('./dag'),
   libp2p: require('./libp2p'),
   object: require('./object')
 }