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// Licensed to the Software Freedom Conservancy (SFC) under one
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// or more contributor license agreements.  See the NOTICE file
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// distributed with this work for additional information
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// regarding copyright ownership.  The SFC licenses this file
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// to you under the Apache License, Version 2.0 (the
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// "License"); you may not use this file except in compliance
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// with the License.  You may obtain a copy of the License at
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//
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//   http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing,
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// software distributed under the License is distributed on an
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// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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// KIND, either express or implied.  See the License for the
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// specific language governing permissions and limitations
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// under the License.
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use crate::logger::Logger;
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use anyhow::Error;
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use std::cell::RefCell;
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use std::fs::File;
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use std::path::{Path, PathBuf};
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use crate::files::{create_parent_path_if_not_exists, create_path_if_not_exists};
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use fs2::FileExt;
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use std::fs;
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thread_local!(static LOCK_PATH: RefCell<Option<PathBuf>> = const { RefCell::new(None) });
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const LOCK_FILE: &str = "sm.lock";
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pub struct Lock {
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    file: File,
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    path: PathBuf,
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}
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impl Lock {
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    // Acquire file lock to prevent race conditions accessing the cache folder by concurrent SM processes
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    pub fn acquire(
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        log: &Logger,
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        target: &Path,
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        single_file: Option<String>,
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    ) -> Result<Self, Error> {
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        let lock_folder = if single_file.is_some() {
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            create_parent_path_if_not_exists(target)?;
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            target.parent().unwrap()
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        } else {
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            create_path_if_not_exists(target)?;
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            target
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        };
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        let path = lock_folder.join(LOCK_FILE);
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        let file = File::create(&path)?;
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        log.debug(format!("Acquiring lock: {}", path.display()));
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        file.lock_exclusive().unwrap_or_default();
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        set_lock_path(Some(path.to_path_buf()));
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        Ok(Self { file, path })
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    }
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    pub fn release(&mut self) {
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        fs::remove_file(&self.path).unwrap_or_default();
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        self.file.unlock().unwrap_or_default();
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        set_lock_path(None);
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    }
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    pub fn exists(&mut self) -> bool {
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        self.path.exists()
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    }
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}
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pub fn clear_lock_if_required() {
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    let lock_path = get_lock_path();
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    if lock_path.is_some() {
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        let lock = lock_path.unwrap();
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        if lock.exists() {
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            fs::remove_file(lock).unwrap_or_default();
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        }
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    }
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}
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fn set_lock_path(path: Option<PathBuf>) {
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    LOCK_PATH.with(|lock_path| {
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        *lock_path.borrow_mut() = path;
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    });
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}
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fn get_lock_path() -> Option<PathBuf> {
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    LOCK_PATH.with(|lock_path| lock_path.borrow().clone())
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}
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