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// Copyright 2020 TiKV Project Authors. Licensed under Apache-2.0.

use crate::storage::kv::WriteData;
use crate::storage::lock_manager::LockManager;
use crate::storage::mvcc::{MvccTxn, SnapshotReader};
use crate::storage::txn::commands::{
    Command, CommandExt, ReleasedLocks, ResponsePolicy, TypedCommand, WriteCommand, WriteContext,
    WriteResult,
};
use crate::storage::txn::{cleanup, commit, Result};
use crate::storage::{ProcessResult, Snapshot};
use txn_types::{Key, TimeStamp};

command! {
    /// Resolve locks on `resolve_keys` according to `start_ts` and `commit_ts`.
    ResolveLockLite:
        cmd_ty => (),
        display => "kv::resolve_lock_lite", (),
        content => {
            /// The transaction timestamp.
            start_ts: TimeStamp,
            /// The transaction commit timestamp.
            commit_ts: TimeStamp,
            /// The keys to resolve.
            resolve_keys: Vec<Key>,
        }
}

impl CommandExt for ResolveLockLite {
    ctx!();
    tag!(resolve_lock_lite);
    ts!(start_ts);
    command_method!(is_sys_cmd, bool, true);
    write_bytes!(resolve_keys: multiple);
    gen_lock!(resolve_keys: multiple);
}

impl<S: Snapshot, L: LockManager> WriteCommand<S, L> for ResolveLockLite {
    fn process_write(self, snapshot: S, context: WriteContext<'_, L>) -> Result<WriteResult> {
        let mut txn = MvccTxn::new(self.start_ts, context.concurrency_manager);
        let mut reader =
            SnapshotReader::new(self.start_ts, snapshot, !self.ctx.get_not_fill_cache());

        let rows = self.resolve_keys.len();
        // ti-client guarantees the size of resolve_keys will not too large, so no necessary
        // to control the write_size as ResolveLock.
        let mut released_locks = ReleasedLocks::new(self.start_ts, self.commit_ts);
        for key in self.resolve_keys {
            released_locks.push(if !self.commit_ts.is_zero() {
                commit(&mut txn, &mut reader, key, self.commit_ts)?
            } else {
                cleanup(&mut txn, &mut reader, key, TimeStamp::zero(), false)?
            });
        }
        released_locks.wake_up(context.lock_mgr);

        context.statistics.add(&reader.take_statistics());
        let write_data = WriteData::from_modifies(txn.into_modifies());
        Ok(WriteResult {
            ctx: self.ctx,
            to_be_write: write_data,
            rows,
            pr: ProcessResult::Res,
            lock_info: None,
            lock_guards: vec![],
            response_policy: ResponsePolicy::OnApplied,
        })
    }
}