82 lines
4.1 KiB
Go
82 lines
4.1 KiB
Go
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// Copyright (c) 2016 The btcsuite developers
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// Use of this source code is governed by an ISC
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// license that can be found in the LICENSE file.
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/*
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Package mempool provides a policy-enforced pool of unmined bitcoin transactions.
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A key responsbility of the bitcoin network is mining user-generated transactions
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into blocks. In order to facilitate this, the mining process relies on having a
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readily-available source of transactions to include in a block that is being
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solved.
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At a high level, this package satisfies that requirement by providing an
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in-memory pool of fully validated transactions that can also optionally be
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further filtered based upon a configurable policy.
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One of the policy configuration options controls whether or not "standard"
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transactions are accepted. In essence, a "standard" transaction is one that
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satisfies a fairly strict set of requirements that are largley intended to help
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provide fair use of the system to all users. It is important to note that what
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is considered a "standard" transaction changes over time. For some insight, at
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the time of this writing, an example of SOME of the criteria that are required
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for a transaction to be considered standard are that it is of the most-recently
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supported version, finalized, does not exceed a specific size, and only consists
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of specific script forms.
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Since this package does not deal with other bitcoin specifics such as network
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communication and transaction relay, it returns a list of transactions that were
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accepted which gives the caller a high level of flexibility in how they want to
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proceed. Typically, this will involve things such as relaying the transactions
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to other peers on the network and notifying the mining process that new
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transactions are available.
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Feature Overview
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The following is a quick overview of the major features. It is not intended to
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be an exhaustive list.
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- Maintain a pool of fully validated transactions
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- Reject non-fully-spent duplicate transactions
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- Reject coinbase transactions
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- Reject double spends (both from the chain and other transactions in pool)
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- Reject invalid transactions according to the network consensus rules
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- Full script execution and validation with signature cache support
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- Individual transaction query support
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- Orphan transaction support (transactions that spend from unknown outputs)
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- Configurable limits (see transaction acceptance policy)
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- Automatic addition of orphan transactions that are no longer orphans as new
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transactions are added to the pool
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- Individual orphan transaction query support
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- Configurable transaction acceptance policy
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- Option to accept or reject standard transactions
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- Option to accept or reject transactions based on priority calculations
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- Rate limiting of low-fee and free transactions
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- Non-zero fee threshold
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- Max signature operations per transaction
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- Max orphan transaction size
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- Max number of orphan transactions allowed
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- Additional metadata tracking for each transaction
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- Timestamp when the transaction was added to the pool
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- Most recent block height when the transaction was added to the pool
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- The fee the transaction pays
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- The starting priority for the transaction
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- Manual control of transaction removal
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- Recursive removal of all dependent transactions
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Errors
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Errors returned by this package are either the raw errors provided by underlying
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calls or of type mempool.RuleError. Since there are two classes of rules
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(mempool acceptance rules and blockchain (consensus) acceptance rules), the
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mempool.RuleError type contains a single Err field which will, in turn, either
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be a mempool.TxRuleError or a blockchain.RuleError. The first indicates a
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violation of mempool acceptance rules while the latter indicates a violation of
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consensus acceptance rules. This allows the caller to easily differentiate
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between unexpected errors, such as database errors, versus errors due to rule
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violations through type assertions. In addition, callers can programmatically
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determine the specific rule violation by type asserting the Err field to one of
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the aforementioned types and examining their underlying ErrorCode field.
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*/
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package mempool
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