Merge branch 'master' into mascara-deploy

1 files changed, 110 insertions, 0 deletions

diff --git a/app/scripts/controllers/recent-blocks.js b/app/scripts/controllers/recent-blocks.js
new file mode 100644
index 000000000..4ae3810eb
--- /dev/null
+++ b/app/scripts/controllers/recent-blocks.js
@@ -0,0 +1,110 @@
+const ObservableStore = require('obs-store')
+const extend = require('xtend')
+const BN = require('ethereumjs-util').BN
+const EthQuery = require('eth-query')
+
+class RecentBlocksController {
+
+  constructor (opts = {}) {
+    const { blockTracker, provider } = opts
+    this.blockTracker = blockTracker
+    this.ethQuery = new EthQuery(provider)
+    this.historyLength = opts.historyLength || 40
+
+    const initState = extend({
+      recentBlocks: [],
+    }, opts.initState)
+    this.store = new ObservableStore(initState)
+
+    this.blockTracker.on('block', this.processBlock.bind(this))
+    this.backfill()
+  }
+
+  resetState () {
+    this.store.updateState({
+      recentBlocks: [],
+    })
+  }
+
+  processBlock (newBlock) {
+    const block = this.mapTransactionsToPrices(newBlock)
+
+    const state = this.store.getState()
+    state.recentBlocks.push(block)
+
+    while (state.recentBlocks.length > this.historyLength) {
+      state.recentBlocks.shift()
+    }
+
+    this.store.updateState(state)
+  }
+
+  backfillBlock (newBlock) {
+    const block = this.mapTransactionsToPrices(newBlock)
+
+    const state = this.store.getState()
+
+    if (state.recentBlocks.length < this.historyLength) {
+      state.recentBlocks.unshift(block)
+    }
+
+    this.store.updateState(state)
+  }
+
+  mapTransactionsToPrices (newBlock) {
+    const block = extend(newBlock, {
+      gasPrices: newBlock.transactions.map((tx) => {
+        return tx.gasPrice
+      }),
+    })
+    delete block.transactions
+    return block
+  }
+
+  async backfill() {
+    this.blockTracker.once('block', async (block) => {
+      let blockNum = block.number
+      let recentBlocks
+      let state = this.store.getState()
+      recentBlocks = state.recentBlocks
+
+      while (recentBlocks.length < this.historyLength) {
+        try {
+          let blockNumBn = new BN(blockNum.substr(2), 16)
+          const newNum = blockNumBn.subn(1).toString(10)
+          const newBlock = await this.getBlockByNumber(newNum)
+
+          if (newBlock) {
+            this.backfillBlock(newBlock)
+            blockNum = newBlock.number
+          }
+
+          state = this.store.getState()
+          recentBlocks = state.recentBlocks
+        } catch (e) {
+          log.error(e)
+        }
+        await this.wait()
+      }
+    })
+  }
+
+  async wait () {
+    return new Promise((resolve) => {
+      setTimeout(resolve, 100)
+    })
+  }
+
+  async getBlockByNumber (number) {
+    const bn = new BN(number)
+    return new Promise((resolve, reject) => {
+      this.ethQuery.getBlockByNumber('0x' + bn.toString(16), true, (err, block) => {
+        if (err) reject(err)
+        resolve(block)
+      })
+    })
+  }
+
+}
+
+module.exports = RecentBlocksController