[pbs-devel] [PATCH proxmox-backup v2 2/9] config: add JobState helper

[Dominik Csapak]

this is intended to be a generic helper to (de)serialize job states
(e.g., sync, verify, and so on)

writes a json file into '/var/lib/proxmox-backup/jobstates/TYPE-ID.json'

the api creates the directory with the correct permissions, like
the rrd directory

Signed-off-by: Dominik Csapak <d.csapak at proxmox.com>
---
changes from v1:
* JobState is now an enum
* use dietmars suggestions
 src/bin/proxmox-backup-api.rs |   1 +
 src/config.rs                 |   1 +
 src/config/jobstate.rs        | 125 ++++++++++++++++++++++++++++++++++
 3 files changed, 127 insertions(+)
 create mode 100644 src/config/jobstate.rs

diff --git a/src/bin/proxmox-backup-api.rs b/src/bin/proxmox-backup-api.rs
index 9dde46c0..ea306cf0 100644
--- a/src/bin/proxmox-backup-api.rs
+++ b/src/bin/proxmox-backup-api.rs
@@ -37,6 +37,7 @@ async fn run() -> Result<(), Error> {
     config::update_self_signed_cert(false)?;
 
     proxmox_backup::rrd::create_rrdb_dir()?;
+    proxmox_backup::config::jobstate::create_jobstate_dir()?;
 
     if let Err(err) = generate_auth_key() {
         bail!("unable to generate auth key - {}", err);
diff --git a/src/config.rs b/src/config.rs
index 2aeccaec..c2ac6da1 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -18,6 +18,7 @@ use crate::buildcfg;
 pub mod acl;
 pub mod cached_user_info;
 pub mod datastore;
+pub mod jobstate;
 pub mod network;
 pub mod remote;
 pub mod sync;
diff --git a/src/config/jobstate.rs b/src/config/jobstate.rs
new file mode 100644
index 00000000..0e8a3115
--- /dev/null
+++ b/src/config/jobstate.rs
@@ -0,0 +1,125 @@
+use std::fs::File;
+use std::path::{Path, PathBuf};
+use std::time::Duration;
+
+use serde::{Serialize, Deserialize};
+use anyhow::{bail, Error, format_err};
+use proxmox::tools::fs::{file_read_optional_string, replace_file, create_path, CreateOptions, open_file_locked};
+
+use crate::tools::epoch_now_u64;
+use crate::server::TaskState;
+
+#[serde(rename_all="kebab-case")]
+#[derive(Serialize,Deserialize)]
+pub enum JobState {
+    Created { time: i64 },
+    Started { upid: String },
+    Finished { upid: String, endtime: i64, state: TaskState }
+}
+
+const JOB_STATE_BASEDIR: &str = "/var/lib/proxmox-backup/jobstates";
+
+/// Create jobstate stat dir with correct permission
+pub fn create_jobstate_dir() -> Result<(), Error> {
+
+    let backup_user = crate::backup::backup_user()?;
+    let opts = CreateOptions::new()
+        .owner(backup_user.uid)
+        .group(backup_user.gid);
+
+    create_path(JOB_STATE_BASEDIR, None, Some(opts))
+        .map_err(|err: Error| format_err!("unable to create rrdb stat dir - {}", err))?;
+
+    Ok(())
+}
+
+fn get_path(jobtype: &str, jobname: &str) -> Result<PathBuf, Error> {
+    let mut path = PathBuf::from(JOB_STATE_BASEDIR);
+    path.push(format!("{}-{}.json", jobtype, jobname));
+    Ok(path)
+}
+
+fn get_lock<P>(path: P) -> Result<File, Error>
+where
+    P: AsRef<Path>
+{
+    let mut path = path.as_ref().to_path_buf();
+    path.set_extension("lck");
+    open_file_locked(path, Duration::new(10, 0))
+}
+
+pub fn remove_state_file(jobtype: &str, jobname: &str) -> Result<(), Error> {
+    let path = get_path(jobtype, jobname)?;
+    let _lock = get_lock(&path)?;
+    std::fs::remove_file(&path).map_err(|err|
+        format_err!("cannot remove statefile for {} - {}: {}", jobtype, jobname, err)
+    )
+}
+
+impl JobState {
+    pub fn new(upid: &str) -> Self {
+        JobState::Started{
+            upid: upid.to_string(),
+        }
+    }
+
+    pub fn finish(&mut self, state: TaskState) -> Result<(), Error> {
+        let upid = match self {
+            JobState::Created { .. } => bail!("cannot finish when not started"),
+            JobState::Started { upid } => upid,
+            JobState::Finished { upid, .. } => upid,
+        }.to_string();
+
+        let endtime: i64 = epoch_now_u64()? as i64;
+
+        *self = JobState::Finished {
+            upid,
+            endtime,
+            state,
+        };
+
+        Ok(())
+    }
+
+    pub fn try_read_or_create(jobtype: &str, jobname: &str) -> Result<Self, Error> {
+        let path = get_path(jobtype, jobname)?;
+
+        let lock = get_lock(&path)?;
+
+        if let Some(state) = file_read_optional_string(path)? {
+            Ok(serde_json::from_str(&state)?)
+        } else {
+            let state = JobState::Created {
+                time: epoch_now_u64()? as i64
+            };
+            state.write_state(jobtype, jobname, Some(lock))?;
+            Ok(state)
+        }
+    }
+
+    pub fn write_state(&self, jobtype: &str, jobname: &str, lock: Option<File>) -> Result<(), Error> {
+        let serialized = serde_json::to_string(&self)?;
+        let path = get_path(jobtype, jobname)?;
+
+        let _lock = if let Some(lock) = lock {
+            lock
+        } else {
+            get_lock(&path)?
+        };
+
+        let backup_user = crate::backup::backup_user()?;
+        let mode = nix::sys::stat::Mode::from_bits_truncate(0o0644);
+        // set the correct owner/group/permissions while saving file
+        // owner(rw) = backup, group(r)= backup
+        let options = CreateOptions::new()
+            .perm(mode)
+            .owner(backup_user.uid)
+            .group(backup_user.gid);
+
+        replace_file(
+            path,
+            serialized.as_bytes(),
+            options,
+        )
+    }
+}
-- 
2.20.1