1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103

// This file is part of Substrate.

// Copyright (C) 2017-2021 Parity Technologies (UK) Ltd.
// SPDX-License-Identifier: GPL-3.0-or-later WITH Classpath-exception-2.0

// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program. If not, see <https://www.gnu.org/licenses/>.

use crate::error::Error;
use codec::Encode;
use futures::{future, prelude::*};
use log::info;
use sp_runtime::{
	generic::BlockId,
	traits::{Block as BlockT, NumberFor, One, SaturatedConversion, Zero},
};

use sc_client_api::{BlockBackend, UsageProvider};
use std::{io::Write, pin::Pin, sync::Arc, task::Poll};

/// Performs the blocks export.
pub fn export_blocks<B, C>(
	client: Arc<C>,
	mut output: impl Write + 'static,
	from: NumberFor<B>,
	to: Option<NumberFor<B>>,
	binary: bool,
) -> Pin<Box<dyn Future<Output = Result<(), Error>>>>
where
	C: BlockBackend<B> + UsageProvider<B> + 'static,
	B: BlockT,
{
	let mut block = from;

	let last = match to {
		Some(v) if v.is_zero() => One::one(),
		Some(v) => v,
		None => client.usage_info().chain.best_number,
	};

	let mut wrote_header = false;

	// Exporting blocks is implemented as a future, because we want the operation to be
	// interruptible.
	//
	// Every time we write a block to the output, the `Future` re-schedules itself and returns
	// `Poll::Pending`.
	// This makes it possible either to interleave other operations in-between the block exports,
	// or to stop the operation completely.
	let export = future::poll_fn(move |cx| {
		let client = &client;

		if last < block {
			return Poll::Ready(Err("Invalid block range specified".into()))
		}

		if !wrote_header {
			info!("Exporting blocks from #{} to #{}", block, last);
			if binary {
				let last_: u64 = last.saturated_into::<u64>();
				let block_: u64 = block.saturated_into::<u64>();
				let len: u64 = last_ - block_ + 1;
				output.write_all(&len.encode())?;
			}
			wrote_header = true;
		}

		match client.block(&BlockId::number(block))? {
			Some(block) =>
				if binary {
					output.write_all(&block.encode())?;
				} else {
					serde_json::to_writer(&mut output, &block)
						.map_err(|e| format!("Error writing JSON: {}", e))?;
				},
			// Reached end of the chain.
			None => return Poll::Ready(Ok(())),
		}
		if (block % 10000u32.into()).is_zero() {
			info!("#{}", block);
		}
		if block == last {
			return Poll::Ready(Ok(()))
		}
		block += One::one();

		// Re-schedule the task in order to continue the operation.
		cx.waker().wake_by_ref();
		Poll::Pending
	});

	Box::pin(export)
}