proxmox-rrd: avoild blocking readers while applying the journal
By using and extra RwLock<RRDMap> on the rrd data.
This commit is contained in:
Dietmar Maurer
parent
658357c5a8
commit
fce7cd0d36
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@ -24,14 +24,88 @@ pub struct RRDCache {
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apply_interval: f64,
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basedir: PathBuf,
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file_options: CreateOptions,
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dir_options: CreateOptions,
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state: RwLock<RRDCacheState>,
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load_rrd_cb: fn(cache: &RRDCache, path: &Path, rel_path: &str, dst: DST) -> RRD,
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rrd_map: RwLock<RRDMap>,
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}
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struct RRDMap {
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basedir: PathBuf,
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file_options: CreateOptions,
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dir_options: CreateOptions,
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map: HashMap<String, RRD>,
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load_rrd_cb: fn(path: &Path, rel_path: &str, dst: DST) -> RRD,
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}
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impl RRDMap {
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fn update(
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&mut self,
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rel_path: &str,
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time: f64,
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value: f64,
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dst: DST,
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new_only: bool,
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) -> Result<(), Error> {
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if let Some(rrd) = self.map.get_mut(rel_path) {
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if !new_only || time > rrd.last_update() {
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rrd.update(time, value);
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}
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} else {
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let mut path = self.basedir.clone();
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path.push(rel_path);
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create_path(path.parent().unwrap(), Some(self.dir_options.clone()), Some(self.dir_options.clone()))?;
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let mut rrd = (self.load_rrd_cb)(&path, rel_path, dst);
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if !new_only || time > rrd.last_update() {
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rrd.update(time, value);
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}
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self.map.insert(rel_path.to_string(), rrd);
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}
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Ok(())
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}
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fn flush_rrd_files(&self) -> Result<usize, Error> {
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let mut rrd_file_count = 0;
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let mut errors = 0;
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for (rel_path, rrd) in self.map.iter() {
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rrd_file_count += 1;
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let mut path = self.basedir.clone();
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path.push(&rel_path);
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if let Err(err) = rrd.save(&path, self.file_options.clone()) {
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errors += 1;
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log::error!("unable to save {:?}: {}", path, err);
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}
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}
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if errors != 0 {
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bail!("errors during rrd flush - unable to commit rrd journal");
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}
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Ok(rrd_file_count)
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}
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fn extract_cached_data(
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&self,
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base: &str,
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name: &str,
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cf: CF,
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resolution: u64,
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start: Option<u64>,
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end: Option<u64>,
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) -> Result<Option<(u64, u64, Vec<Option<f64>>)>, Error> {
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match self.map.get(&format!("{}/{}", base, name)) {
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Some(rrd) => Ok(Some(rrd.extract_data(cf, resolution, start, end)?)),
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None => Ok(None),
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}
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}
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}
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// shared state behind RwLock
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struct RRDCacheState {
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rrd_map: HashMap<String, RRD>,
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journal: File,
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last_journal_flush: f64,
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journal_applied: bool,
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@ -65,7 +139,7 @@ impl RRDCache {
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file_options: Option<CreateOptions>,
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dir_options: Option<CreateOptions>,
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apply_interval: f64,
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load_rrd_cb: fn(cache: &RRDCache, path: &Path, rel_path: &str, dst: DST) -> RRD,
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load_rrd_cb: fn(path: &Path, rel_path: &str, dst: DST) -> RRD,
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) -> Result<Self, Error> {
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let basedir = basedir.as_ref().to_owned();
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@ -83,18 +157,24 @@ impl RRDCache {
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let state = RRDCacheState {
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journal,
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rrd_map: HashMap::new(),
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last_journal_flush: 0.0,
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journal_applied: false,
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};
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let rrd_map = RRDMap {
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basedir: basedir.clone(),
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file_options: file_options.clone(),
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dir_options: dir_options,
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map: HashMap::new(),
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load_rrd_cb,
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};
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Ok(Self {
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basedir,
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file_options,
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dir_options,
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apply_interval,
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load_rrd_cb,
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state: RwLock::new(state),
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rrd_map: RwLock::new(rrd_map),
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})
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}
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@ -221,17 +301,7 @@ impl RRDCache {
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let journal = atomic_open_or_create_file(&journal_path, flags, &[], self.file_options.clone())?;
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let mut journal = BufReader::new(journal);
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let mut last_update_map = HashMap::new();
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let mut get_last_update = |rel_path: &str, rrd: &RRD| {
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if let Some(time) = last_update_map.get(rel_path) {
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return *time;
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}
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let last_update = rrd.last_update();
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last_update_map.insert(rel_path.to_string(), last_update);
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last_update
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};
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// fixme: apply blocked to avoid too many calls to self.rrd_map.write() ??
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let mut linenr = 0;
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loop {
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linenr += 1;
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@ -247,24 +317,8 @@ impl RRDCache {
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}
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};
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if let Some(rrd) = state.rrd_map.get_mut(&entry.rel_path) {
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if entry.time > get_last_update(&entry.rel_path, &rrd) {
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rrd.update(entry.time, entry.value);
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self.rrd_map.write().unwrap().update(&entry.rel_path, entry.time, entry.value, entry.dst, true)?;
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}
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} else {
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let mut path = self.basedir.clone();
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path.push(&entry.rel_path);
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create_path(path.parent().unwrap(), Some(self.dir_options.clone()), Some(self.dir_options.clone()))?;
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let mut rrd = (self.load_rrd_cb)(&self, &path, &entry.rel_path, entry.dst);
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if entry.time > get_last_update(&entry.rel_path, &rrd) {
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rrd.update(entry.time, entry.value);
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}
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state.rrd_map.insert(entry.rel_path.clone(), rrd);
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}
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}
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// We need to apply the journal only once, because further updates
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// are always directly applied.
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@ -275,23 +329,8 @@ impl RRDCache {
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fn commit_journal_locked(&self, state: &mut RRDCacheState) -> Result<usize, Error> {
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// save all RRDs
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let mut rrd_file_count = 0;
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let mut errors = 0;
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for (rel_path, rrd) in state.rrd_map.iter() {
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rrd_file_count += 1;
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let mut path = self.basedir.clone();
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path.push(&rel_path);
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if let Err(err) = rrd.save(&path, self.file_options.clone()) {
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errors += 1;
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log::error!("unable to save {:?}: {}", path, err);
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}
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}
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if errors != 0 {
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bail!("errors during rrd flush - unable to commit rrd journal");
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}
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// save all RRDs - we only need a read lock here
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let rrd_file_count = self.rrd_map.read().unwrap().flush_rrd_files()?;
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// if everything went ok, commit the journal
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@ -318,18 +357,7 @@ impl RRDCache {
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Self::append_journal_entry(&mut state, time, value, dst, rel_path)?;
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if let Some(rrd) = state.rrd_map.get_mut(rel_path) {
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rrd.update(time, value);
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} else {
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let mut path = self.basedir.clone();
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path.push(rel_path);
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create_path(path.parent().unwrap(), Some(self.dir_options.clone()), Some(self.dir_options.clone()))?;
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let mut rrd = (self.load_rrd_cb)(&self, &path, rel_path, dst);
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rrd.update(time, value);
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state.rrd_map.insert(rel_path.into(), rrd);
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}
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self.rrd_map.write().unwrap().update(rel_path, time, value, dst, false)?;
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Ok(())
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}
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@ -348,12 +376,7 @@ impl RRDCache {
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start: Option<u64>,
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end: Option<u64>,
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) -> Result<Option<(u64, u64, Vec<Option<f64>>)>, Error> {
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let state = self.state.read().unwrap();
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match state.rrd_map.get(&format!("{}/{}", base, name)) {
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Some(rrd) => Ok(Some(rrd.extract_data(cf, resolution, start, end)?)),
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None => Ok(None),
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}
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self.rrd_map.read().unwrap()
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.extract_cached_data(base, name, cf, resolution, start, end)
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}
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}
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@ -48,7 +48,6 @@ pub fn initialize_rrd_cache() -> Result<&'static RRDCache, Error> {
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}
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fn load_callback(
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_cache: &RRDCache,
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path: &Path,
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_rel_path: &str,
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dst: DST,
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