Release v0.1.0

vendor/github.com/btcsuite/btcd/database/doc.go

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+// Copyright (c) 2015-2016 The btcsuite developers
+// Use of this source code is governed by an ISC
+// license that can be found in the LICENSE file.
+
+/*
+Package database provides a block and metadata storage database.
+
+Overview
+
+As of Feb 2016, there are over 400,000 blocks in the Bitcoin block chain and
+and over 112 million transactions (which turns out to be over 60GB of data).
+This package provides a database layer to store and retrieve this data in a
+simple and efficient manner.
+
+The default backend, ffldb, has a strong focus on speed, efficiency, and
+robustness.  It makes use leveldb for the metadata, flat files for block
+storage, and strict checksums in key areas to ensure data integrity.
+
+A quick overview of the features database provides are as follows:
+
+ - Key/value metadata store
+ - Bitcoin block storage
+ - Efficient retrieval of block headers and regions (transactions, scripts, etc)
+ - Read-only and read-write transactions with both manual and managed modes
+ - Nested buckets
+ - Supports registration of backend databases
+ - Comprehensive test coverage
+
+Database
+
+The main entry point is the DB interface.  It exposes functionality for
+transactional-based access and storage of metadata and block data.  It is
+obtained via the Create and Open functions which take a database type string
+that identifies the specific database driver (backend) to use as well as
+arguments specific to the specified driver.
+
+The interface provides facilities for obtaining transactions (the Tx interface)
+that are the basis of all database reads and writes.  Unlike some database
+interfaces that support reading and writing without transactions, this interface
+requires transactions even when only reading or writing a single key.
+
+The Begin function provides an unmanaged transaction while the View and Update
+functions provide a managed transaction.  These are described in more detail
+below.
+
+Transactions
+
+The Tx interface provides facilities for rolling back or committing changes that
+took place while the transaction was active.  It also provides the root metadata
+bucket under which all keys, values, and nested buckets are stored.  A
+transaction can either be read-only or read-write and managed or unmanaged.
+
+Managed versus Unmanaged Transactions
+
+A managed transaction is one where the caller provides a function to execute
+within the context of the transaction and the commit or rollback is handled
+automatically depending on whether or not the provided function returns an
+error.  Attempting to manually call Rollback or Commit on the managed
+transaction will result in a panic.
+
+An unmanaged transaction, on the other hand, requires the caller to manually
+call Commit or Rollback when they are finished with it.  Leaving transactions
+open for long periods of time can have several adverse effects, so it is
+recommended that managed transactions are used instead.
+
+Buckets
+
+The Bucket interface provides the ability to manipulate key/value pairs and
+nested buckets as well as iterate through them.
+
+The Get, Put, and Delete functions work with key/value pairs, while the Bucket,
+CreateBucket, CreateBucketIfNotExists, and DeleteBucket functions work with
+buckets.  The ForEach function allows the caller to provide a function to be
+called with each key/value pair and nested bucket in the current bucket.
+
+Metadata Bucket
+
+As discussed above, all of the functions which are used to manipulate key/value
+pairs and nested buckets exist on the Bucket interface.  The root metadata
+bucket is the upper-most bucket in which data is stored and is created at the
+same time as the database.  Use the Metadata function on the Tx interface
+to retrieve it.
+
+Nested Buckets
+
+The CreateBucket and CreateBucketIfNotExists functions on the Bucket interface
+provide the ability to create an arbitrary number of nested buckets.  It is
+a good idea to avoid a lot of buckets with little data in them as it could lead
+to poor page utilization depending on the specific driver in use.
+*/
+package database