services: add new service for fetching blocks from NeoFS

Close #3496

Co-authored-by: Anna Shaleva <shaleva.ann@nspcc.ru>
Signed-off-by: Ekaterina Pavlova <ekt@morphbits.io>

Author: AliceInHunterland

config/protocol.testnet.yml

@@ -100,3 +100,16 @@ ApplicationConfiguration:
     Enabled: false
     Addresses:
       - ":2113"
+  NeoFSBlockFetcher:
+    Enabled: false
+    Addresses:
+      - st1.storage.fs.neo.org:8080
+    Timeout: 10m
+    DownloaderWorkersCount: 500
+    OIDBatchSize: 8000
+    BQueueSize: 16000 # must be larger than OIDBatchSize; recommended to be 2*OIDBatchSize or 3*OIDBatchSize
+    SkipIndexFilesSearch: false
+    IndexFileSize: 128000
+    ContainerID: "EPGuD26wYgQJbmDdVBoYoNZiMKHwFMJT3A5WqPjdUHxH"
+    BlockAttribute: "block"
+    IndexFileAttribute: "oid"

docs/neofs-blockstorage.md

@@ -0,0 +1,74 @@
+# NeoFS block storage
+
+Using NeoFS to store chain's blocks and snapshots was proposed in
+[#3463](https://github.com/neo-project/neo/issues/3463). NeoGo contains several
+extensions utilizing NeoFS block storage aimed to improve node synchronization
+efficiency and reduce node storage size.
+
+## Components and functionality
+
+### Block storage schema
+
+A single NeoFS container is used to store blocks and index files. Each block
+is stored in a binary form as a separate object with a unique OID and a set of
+attributes:
+ - block object identifier with block index value (`block:1`)
+ - primary node index (`primary:0`)
+ - block hash in the LE form (`hash:5412a781caf278c0736556c0e544c7cfdbb6e3c62ae221ef53646be89364566b`)
+ - previous block hash in the LE form (`prevHash:3654a054d82a8178c7dfacecc2c57282e23468a42ee407f14506368afe22d929`)
+ - millisecond-precision block timestamp (`time:1627894840919`)
+
+Each index file is an object containing a constant-sized batch of raw block object
+IDs in binary form ordered by block index. Each index file is marked with the
+following attributes:
+ - index file identifier with consecutive file index value (`oid:0`)
+ - the number of OIDs included into index file (`size:128000`)
+
+### NeoFS BlockFetcher
+
+NeoFS BlockFetcher service is designed as an alternative to P2P synchronisation
+protocol. It allows to download blocks from a trusted container in the NeoFS network
+and persist them to database using standard verification flow. NeoFS BlockFetcher
+service primarily used during the node's bootstrap, providing a fast alternative to
+P2P blocks synchronisation.
+
+NeoFS BlockFetcher service has two modes of operation:
+- Index File Search: Search for index files, which contain batches of block object
+  IDs and fetch blocks from NeoFS by retrieved OIDs.
+- Direct Block Search: Search and fetch blocks directly from NeoFS container via
+  built-in NeoFS object search mechanism.
+
+Operation mode of BlockFetcher can be configured via `SkipIndexFilesSearch`
+parameter.
+
+#### Operation flow
+
+1. **OID Fetching**:
+    Depending on the mode, the service either:
+   - Searches for index files by index file attribute and reads block OIDs from index
+     file object-by-object.
+   - Searches batches of blocks directly by block attribute (the batch size is
+     configured via `OIDBatchSize` parameter).
+
+   Once the OIDs are retrieved, they are immediately redirected to the 
+   block downloading routines for further processing. The channel that 
+   is used to redirect block OIDs to downloading routines is buffered 
+   to provide smooth OIDs delivery without delays. The size of this channel 
+   can be configured via `OIDBatchSize` parameter and equals to `2*OIDBatchSize`.
+2. **Parallel Block Downloading**:
+   The number of downloading routines can be configured via 
+   `DownloaderWorkersCount` parameter. It's up to the user to find the 
+   balance between the downloading speed and blocks persist speed for every 
+   node that uses NeoFS BlockFetcher. Downloaded blocks are placed into a 
+   buffered channel of size `IDBatchSize` with further redirection to the
+   block queue.
+3. **Block Insertion**:
+   Downloaded blocks are inserted into the blockchain using the same logic
+   as in the P2P synchronisation protocol. The block queue is used to order 
+   downloaded blocks before they are inserted into the blockchain. The 
+   size of the queue can be configured via the `BQueueSize` parameter 
+   and should be larger than the `OIDBatchSize` parameter to avoid blocking
+   the downloading routines.
+
+Once all blocks available in the NeoFS container are processed, the service
+shuts down automatically.

docs/node-configuration.md

@@ -21,6 +21,7 @@ node-related settings described in the table below.
 | GarbageCollectionPeriod | `uint32` | 10000 | Controls MPT garbage collection interval (in blocks) for configurations with `RemoveUntraceableBlocks` enabled and `KeepOnlyLatestState` disabled. In this mode the node stores a number of MPT trees (corresponding to `MaxTraceableBlocks` and `StateSyncInterval`), but the DB needs to be clean from old entries from time to time. Doing it too often will cause too much processing overhead, doing it too rarely will leave more useless data in the DB. |
 | KeepOnlyLatestState | `bool` | `false` | Specifies if MPT should only store the latest state (or a set of latest states, see `P2PStateExchangeExtensions` section in the ProtocolConfiguration for details). If true, DB size will be smaller, but older roots won't be accessible. This value should remain the same for the same database. |  |
 | LogPath | `string` | "", so only console logging | File path where to store node logs. |
+| NeoFSBlockFetcher | [NeoFS BlockFetcher Configuration](#NeoFS-BlockFetcher-Configuration) | | NeoFS BlockFetcher module configuration. See the [NeoFS BlockFetcher Configuration](#NeoFS-BlockFetcher-Configuration) section for details. |
 | Oracle | [Oracle Configuration](#Oracle-Configuration) | | Oracle module configuration. See the [Oracle Configuration](#Oracle-Configuration) section for details. |
 | P2P | [P2P Configuration](#P2P-Configuration) | | Configuration values for P2P network interaction. See the [P2P Configuration](#P2P-Configuration) section for details. |
 | P2PNotary | [P2P Notary Configuration](#P2P-Notary-Configuration) | | P2P Notary module configuration. See the [P2P Notary Configuration](#P2P-Notary-Configuration) section for details. |
@@ -153,6 +154,55 @@ where:
 Please, refer to the [Notary module documentation](./notary.md#Notary node module) for
 details on module features.
 
+### NeoFS BlockFetcher Configuration
+
+`NeoFSBlockFetcher` configuration section contains settings for NeoFS
+BlockFetcher module and has the following structure:
+```
+  NeoFSBlockFetcher:
+    Enabled: true
+    UnlockWallet:
+      Path: "./wallet.json"
+      Password: "pass"
+    Addresses:
+      - st1.storage.fs.neo.org:8080
+    Timeout: 10m
+    DownloaderWorkersCount: 500
+    OIDBatchSize: 8000
+    BQueueSize: 16000
+    SkipIndexFilesSearch: false
+    ContainerID: "EPGuD26wYgQJbmDdVBoYoNZiMKHwFMJT3A5WqPjdUHxH"
+    BlockAttribute: "block"
+    IndexFileAttribute: "oid"
+    IndexFileSize: 128000
+```
+where:
+- `Enabled` enables NeoFS BlockFetcher module.
+- `UnlockWallet` contains wallet settings to retrieve account to sign requests to
+  NeoFS. Without this setting, the module will use randomly generated private key.
+  For configuration details see [Unlock Wallet Configuration](#Unlock-Wallet-Configuration)
+- `Addresses` is a list of NeoFS storage nodes addresses.
+- `Timeout` is a timeout for a single request to NeoFS storage node.
+- `ContainerID` is a container ID to fetch blocks from.
+- `BlockAttribute` is an attribute name of NeoFS object that contains block
+  data.
+- `IndexFileAttribute` is an attribute name of NeoFS index object that contains block
+  object IDs.
+- `DownloaderWorkersCount` is a number of workers that download blocks from
+  NeoFS in parallel.
+- `OIDBatchSize` is the number of blocks to search per a single request to NeoFS
+  in case of disabled index files search. Also, for both modes of BlockFetcher
+  operation this setting manages the buffer size of OIDs and blocks transferring
+  channels.
+- `BQueueSize` is a size of the block queue used to manage consecutive blocks
+  addition to the chain. It must be larger than `OIDBatchSize` and highly recommended
+  to be `2*OIDBatchSize` or `3*OIDBatchSize`.
+- `SkipIndexFilesSearch` is a flag that allows to skip index files search and search
+  for blocks directly. It is set to `false` by default.
+- `IndexFileSize` is the number of OID objects stored in the index files. This
+  setting depends on the NeoFS block storage configuration and is applicable only if
+  `SkipIndexFilesSearch` is set to `false`.
+
 ### Metrics Services Configuration
 
 Metrics services configuration describes options for metrics services (pprof,

pkg/config/application_config.go

@@ -23,12 +23,13 @@ type ApplicationConfiguration struct {
 	Pprof      BasicService `yaml:"Pprof"`
 	Prometheus BasicService `yaml:"Prometheus"`
 
-	Relay     bool                `yaml:"Relay"`
-	Consensus Consensus           `yaml:"Consensus"`
-	RPC       RPC                 `yaml:"RPC"`
-	Oracle    OracleConfiguration `yaml:"Oracle"`
-	P2PNotary P2PNotary           `yaml:"P2PNotary"`
-	StateRoot StateRoot           `yaml:"StateRoot"`
+	Relay             bool                `yaml:"Relay"`
+	Consensus         Consensus           `yaml:"Consensus"`
+	RPC               RPC                 `yaml:"RPC"`
+	Oracle            OracleConfiguration `yaml:"Oracle"`
+	P2PNotary         P2PNotary           `yaml:"P2PNotary"`
+	StateRoot         StateRoot           `yaml:"StateRoot"`
+	NeoFSBlockFetcher NeoFSBlockFetcher   `yaml:"NeoFSBlockFetcher"`
 }
 
 // EqualsButServices returns true when the o is the same as a except for services
@@ -141,3 +142,13 @@ func (a *ApplicationConfiguration) GetAddresses() ([]AnnounceableAddress, error)
 	}
 	return addrs, nil
 }
+
+// Validate checks ApplicationConfiguration for internal consistency and returns
+// an error if any invalid settings are found. This ensures that the application
+// configuration is valid and safe to use for further operations.
+func (a *ApplicationConfiguration) Validate() error {
+	if err := a.NeoFSBlockFetcher.Validate(); err != nil {
+		return fmt.Errorf("invalid NeoFSBlockFetcher config: %w", err)
+	}
+	return nil
+}

pkg/config/blockfetcher_config.go

@@ -0,0 +1,51 @@
+package config
+
+import (
+	"errors"
+	"fmt"
+	"time"
+
+	cid "github.com/nspcc-dev/neofs-sdk-go/container/id"
+)
+
+// NeoFSBlockFetcher represents the configuration for the NeoFS BlockFetcher service.
+type NeoFSBlockFetcher struct {
+	InternalService        `yaml:",inline"`
+	Timeout                time.Duration `yaml:"Timeout"`
+	ContainerID            string        `yaml:"ContainerID"`
+	Addresses              []string      `yaml:"Addresses"`
+	OIDBatchSize           int           `yaml:"OIDBatchSize"`
+	BlockAttribute         string        `yaml:"BlockAttribute"`
+	IndexFileAttribute     string        `yaml:"IndexFileAttribute"`
+	DownloaderWorkersCount int           `yaml:"DownloaderWorkersCount"`
+	BQueueSize             int           `yaml:"BQueueSize"`
+	SkipIndexFilesSearch   bool          `yaml:"SkipIndexFilesSearch"`
+	IndexFileSize          uint32        `yaml:"IndexFileSize"`
+}
+
+// Validate checks NeoFSBlockFetcher for internal consistency and ensures
+// that all required fields are properly set. It returns an error if the
+// configuration is invalid or if the ContainerID cannot be properly decoded.
+func (cfg *NeoFSBlockFetcher) Validate() error {
+	if !cfg.Enabled {
+		return nil
+	}
+	if cfg.ContainerID == "" {
+		return errors.New("container ID is not set")
+	}
+	var containerID cid.ID
+	err := containerID.DecodeString(cfg.ContainerID)
+	if err != nil {
+		return fmt.Errorf("invalid container ID: %w", err)
+	}
+	if cfg.BQueueSize < cfg.OIDBatchSize {
+		return fmt.Errorf("BQueueSize (%d) is lower than OIDBatchSize (%d)", cfg.BQueueSize, cfg.OIDBatchSize)
+	}
+	if len(cfg.Addresses) == 0 {
+		return errors.New("addresses are not set")
+	}
+	if cfg.IndexFileSize == 0 {
+		return errors.New("IndexFileSize is not set")
+	}
+	return nil
+}

pkg/config/config.go

@@ -116,6 +116,10 @@ func LoadFile(configPath string, relativePath ...string) (Config, error) {
 	if err != nil {
 		return Config{}, err
 	}
+	err = config.ApplicationConfiguration.Validate()
+	if err != nil {
+		return Config{}, err
+	}
 
 	return config, nil
 }