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docs/zagros/deposit/blockchain.md

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+# Blockchain Deposit
+[please read first](daemon.md)
+
+### file:
+- {$Dena_path}/app/workers/daemons/blockchain.rb
+
+### implementation
+daemon dockerize by below code and file:
+- bash -c "bundle exec ruby lib/daemons/daemons.rb blockchain" (called in Alvand Service up rake)
+- {$Dena_path}/lib/daemons/daemons.rb
+
+Blockchain daemon as one **thread** for each active blockchain, process blocks and filter platform deposits.<br />
+this daemon use BlockchainService class in per one thread.<br/>
+that class recognizes its `adapter` (coin-connectors or coin-middleman) with help of the parameter that is passed to it when initialized,
+this parameter is **the blockchain DB record.**<br/>
+also, this class has standard functions that any coin-connectors must obey, so this class has two hands, with one hand connect to local DB and with another hand talk to the relevant Blockchain with help of `the adapter`.<br/>
+each coin has itself adapter that can be the Gem.<br />
+responsibility of these Adapters that connect to the related blockchain and doing my needed methods.<br/>
+this daemon is kept alive by an infinite loop that in every 30 seconds check the active blockchains.<br />
+also, in this 30-second time, check updated time of the blockchain or currencies record, if they have been newly updated time,
+the blockchain thread will be reset.<br />
+when the blockchain thread is reset, the last_seen_block will become **nil**.</br>
+BlockchainService class fetches relative blocks with help the Adapter,<br />
+and find transactions that included our users addresses (users addresses were saved in local DB).<br />
+after each loop of the Blockchain investigation, we update the Variable that has kept the last seen block number.<br />
+and also update the Height column of the blockchain record.<br />
+We are waiting for the N number of confirmations.<br />
+if height column of the blockchain record plus(+) the min confirmation, was bigger than the Adapters last seen block variable, synchronization will be skipped, and try again after 10 seconds<br />
+from the blockchain height to Adapters last_seen_block, the `process_block` function of **BlockchainService** class will be executed for each block.<br/>
+at last the height column will be updated.
+
+#### process_block function
+1. fetch block by Adapter
+2. find relative deposits (destination address of blocks in our user address).
+3. find relative withdraws (hash transaction of blocks in our user confirming withdraws `txid`).
+4. Per deposit Blockchain, we update or create Db record and changing users balances.
+5. Per withdraw in Blockchain, we find Db records by `confirming` state, then update record state by the blockchain transaction,
+   that was fetched before again by its the Adapter. so, at last, we will unlock and update user balances
+
+```mermaid
+graph LR
+A(Peatio) -->|Blockchain stuffs| B[BlockchainService using adapter]
+
+    B --> |Blockchain stuffs| D((Btc Blockchain))
+    B --> |Blockchain stuffs| E((Eth Blockchain))
+    B --> |Blockchain stuffs| F((...))
+    B --> A
+    D --> B
+    E --> B
+    F --> B
+```