From 3275f1ac1615121e50f28e11203577e2b1f74ab1 Mon Sep 17 00:00:00 2001
From: Dietmar Maurer <dietmar@proxmox.com>
Date: Thu, 14 Oct 2021 16:41:08 +0200
Subject: [PATCH] proxmox-rrd: log journal apply/flush times, split apply and
 flush

We need to apply the journal only once.
---
 proxmox-rrd/src/cache.rs | 76 ++++++++++++++++++++++++++++++----------
 1 file changed, 58 insertions(+), 18 deletions(-)

diff --git a/proxmox-rrd/src/cache.rs b/proxmox-rrd/src/cache.rs
index 6cac5849..4c7f05f0 100644
--- a/proxmox-rrd/src/cache.rs
+++ b/proxmox-rrd/src/cache.rs
@@ -5,6 +5,7 @@ use std::sync::RwLock;
 use std::io::Write;
 use std::io::{BufRead, BufReader};
 use std::os::unix::io::AsRawFd;
+use std::time::SystemTime;
 
 use anyhow::{format_err, bail, Error};
 use nix::fcntl::OFlag;
@@ -33,6 +34,7 @@ struct RRDCacheState {
     rrd_map: HashMap<String, RRD>,
     journal: File,
     last_journal_flush: f64,
+    journal_applied: bool,
 }
 
 struct JournalEntry {
@@ -83,6 +85,7 @@ impl RRDCache {
             journal,
             rrd_map: HashMap::new(),
             last_journal_flush: 0.0,
+            journal_applied: false,
         };
 
         Ok(Self {
@@ -171,18 +174,46 @@ impl RRDCache {
         Ok(())
     }
 
-    /// Apply journal. Should be used at server startup.
+    /// Apply and commit the journal. Should be used at server startup.
     pub fn apply_journal(&self) -> Result<(), Error> {
         let mut state = self.state.write().unwrap(); // block writers
-        self.apply_journal_locked(&mut state)
+        self.apply_and_commit_journal_locked(&mut state)
     }
 
-    fn apply_journal_locked(&self, state: &mut RRDCacheState) -> Result<(), Error> {
-
-        log::info!("applying rrd journal");
+    fn apply_and_commit_journal_locked(&self, state: &mut RRDCacheState) -> Result<(), Error> {
 
         state.last_journal_flush = proxmox_time::epoch_f64();
 
+        if !state.journal_applied {
+            let start_time = SystemTime::now();
+            log::debug!("applying rrd journal");
+
+            match self.apply_journal_locked(state) {
+                Ok(entries) => {
+                    let elapsed = start_time.elapsed()?.as_secs_f64();
+                    log::info!("applied rrd journal ({} entries in {:.3} seconds)", entries, elapsed);
+                }
+                Err(err) => bail!("apply rrd journal failed - {}", err),
+            }
+        }
+
+        let start_time = SystemTime::now();
+        log::debug!("commit rrd journal");
+
+        match self.commit_journal_locked(state) {
+            Ok(rrd_file_count) => {
+                let elapsed = start_time.elapsed()?.as_secs_f64();
+                log::info!("rrd journal successfully committed ({} files in {:.3} seconds)",
+                           rrd_file_count, elapsed);
+            }
+            Err(err) => bail!("rrd journal commit failed: {}", err),
+        }
+
+        Ok(())
+    }
+
+    fn apply_journal_locked(&self, state: &mut RRDCacheState) -> Result<usize, Error> {
+
         let mut journal_path = self.basedir.clone();
         journal_path.push(RRD_JOURNAL_NAME);
 
@@ -234,10 +265,22 @@ impl RRDCache {
             }
         }
 
+
+        // We need to apply the journal only once, because further updates
+        // are always directly applied.
+        state.journal_applied = true;
+
+        Ok(linenr)
+    }
+
+    fn commit_journal_locked(&self, state: &mut RRDCacheState) -> Result<usize, Error> {
+
         // save all RRDs
+        let mut rrd_file_count = 0;
 
         let mut errors = 0;
         for (rel_path, rrd) in state.rrd_map.iter() {
+            rrd_file_count += 1;
             let mut path = self.basedir.clone();
             path.push(&rel_path);
             if let Err(err) = rrd.save(&path, self.file_options.clone()) {
@@ -246,17 +289,16 @@ impl RRDCache {
             }
         }
 
-        // if everything went ok, commit the journal
-
-        if errors == 0 {
-            nix::unistd::ftruncate(state.journal.as_raw_fd(), 0)
-                .map_err(|err| format_err!("unable to truncate journal - {}", err))?;
-            log::info!("rrd journal successfully committed");
-        } else {
-            log::error!("errors during rrd flush - unable to commit rrd journal");
+       if errors != 0 {
+            bail!("errors during rrd flush - unable to commit rrd journal");
         }
 
-        Ok(())
+        // if everything went ok, commit the journal
+
+        nix::unistd::ftruncate(state.journal.as_raw_fd(), 0)
+            .map_err(|err| format_err!("unable to truncate journal - {}", err))?;
+
+        Ok(rrd_file_count)
     }
 
     /// Update data in RAM and write file back to disk (journal)
@@ -270,10 +312,8 @@ impl RRDCache {
 
         let mut state = self.state.write().unwrap(); // block other writers
 
-        if (time - state.last_journal_flush) > self.apply_interval {
-            if let Err(err) = self.apply_journal_locked(&mut state) {
-                log::error!("apply journal failed: {}", err);
-            }
+        if !state.journal_applied || (time - state.last_journal_flush) > self.apply_interval {
+            self.apply_and_commit_journal_locked(&mut state)?;
         }
 
         Self::append_journal_entry(&mut state, time, value, dst, rel_path)?;