wip

zfs_autobackup

@@ -456,12 +456,13 @@ class ZfsDataset():
 
     """
 
-    def __init__(self, zfs_node, name, exists=None):
+    def __init__(self, zfs_node, name, force_exists=None):
         """name: full path of the zfs dataset
         exists: specifiy if you already know a dataset exists or not. for performance reasons. (othewise it will have to check with zfs list when needed)
         """
         self.zfs_node=zfs_node
         self.name=name #full name
+        self.force_exists=force_exists
 
     def __repr__(self):
         return("{}: {}".format(self.zfs_node, self.name))
@@ -486,6 +487,7 @@ class ZfsDataset():
         """clear cache"""
         #TODO: nicer?
         self._cached_properties={}
+        self.force_exists=None
 
 
     def lstrip_path(self,count):
@@ -531,13 +533,45 @@ class ZfsDataset():
             return(ZfsDataset(self.zfs_node, self.rstrip_path(1)))
 
 
+    def find_our_prev_snapshot(self, snapshot):
+        """find our previous snapshot in this dataset. None if it doesnt exist"""
+
+        if self.is_snapshot():
+            raise(Exception("Please call this on a dataset.")
+
+        try:
+            index=self.our_snapshots.index(snapshot)
+            if index>0:
+                return(self.our_snapshots[index-1])
+            else:
+                return(None)
+        except:
+            return(None)
+
+
+    def find_our_next_snapshot(self, snapshot):
+        """find our next snapshot in this dataset. None if it doesnt exist"""
+
+        if self.is_snapshot():
+            raise(Exception("Please call this on a dataset.")
+
+        try:
+            index=self.our_snapshots.index(snapshot)
+            if index>=0 and index<len(self.our_snapshots)-1:
+                return(self.our_snapshots[index+1])
+            else:
+                return(None)
+        except:
+            return(None)
+
+
     @cached_property
-    def exists(self, force=None):
+    def exists(self):
         """check if dataset exists.
         Use force to force a specific value to be cached, if you already know. Usefull for performance reasons"""
 
-        if force!=None:
-            return(force)
+        if self.force_exists!=None:
+            return(self.force_exists)
 
         self.debug("Checking if filesystem exists")
         return(self.zfs_node.run(tab_split=True, cmd=[ "zfs", "list", self.name], readonly=True, valid_exitcodes=[ 0,1 ], hide_errors=True) and True)
@@ -560,6 +594,7 @@ class ZfsDataset():
         self.debug("Destroying")
         self.zfs_node.run(["zfs", "destroy", self.name])
         self.invalidate()
+        self.force_exists=False
 
 
     @cached_property
@@ -730,7 +765,7 @@ class ZfsDataset():
 
 
     def recv_pipe(self, pipe, resume=True):
-        """starts a zfs recv on this dataset and uses pipe as input"""
+        """starts a zfs recv for this snapshot and uses pipe as input"""
         #### build target command
         cmd=[]
 
@@ -751,21 +786,25 @@ class ZfsDataset():
             #support resuming
             cmd.append("-s")
 
-        cmd.append(self.name)
+        cmd.append(self.filesystem_name)
 
         self.zfs_node.run(cmd, input=pipe)
 
+        #invalidate cache, but we at least know we exist now
+        self.invalidate()
+        self.force_exists=True
+
         # if args.buffer and  args.ssh_target!="local":
         #     cmd.append("|mbuffer -m {}".format(args.buffer))
 
 
-    def transfer_snapshot(self, target_dataset, prev_snapshot=None, resume=True, resume_token=None, show_progress=False):
-        """transfer this snapshot to target_dataset. specify prev_snapshot for incremental transfer
+    def transfer_snapshot(self, target_snapshot, prev_snapshot=None, resume=True, resume_token=None, show_progress=False):
+        """transfer this snapshot to target_snapshot. specify prev_snapshot for incremental transfer
 
         connects a send_pipe() to recv_pipe()
         """
 
-        self.debug("Transfer snapshot to {}".format(target_dataset))
+        self.debug("Transfer snapshot to {}".format(target_snapshot.filesystem_name))
 
         if resume_token:
             target_dataset.verbose("resuming")
@@ -779,83 +818,79 @@ class ZfsDataset():
 
         #do it
         pipe=self.send_pipe(resume=resume, show_progress=show_progress, resume_token=resume_token, prev_snapshot=prev_snapshot)
-        target_dataset.recv_pipe(pipe)
-
-        #update cache
-        target_dataset.snapshots.append(ZfsDataset(target_dataset.zfs_node, target_dataset.name+"@"+self.snapshot_name))
+        target_snapshot.recv_pipe(pipe)
 
 
-    def thin(self, keep=[]):
+    def thin(self, keeps=[]):
         """determines list of snapshots that should be kept or deleted based on the thinning schedule. cull the herd!
-        keep: list of snapshots to always keep
+        keep: list of snapshots to always keep (usually the last)
         """
-        return(self.zfs_node.thinner.thin(self.our_snapshots, keep_objects=keep))
+        return(self.zfs_node.thinner.thin(self.our_snapshots, keep_objects=keeps))
 
 
+    def find_common_snapshot(self, target_dataset):
+        """find latest coommon snapshot between us and target
+        returns None if its an initial transfer
+        """
+        if not target_dataset.our_snapshots:
+            #we have nothing yet
+            return(None)
+        else:
+            snapshot=self.find_snapshot(target_dataset.our_snapshots[:-1].snapshot_name)
+            if not snapshot:
+                raise(Exception("Cant find latest target snapshot on source"))
+
     def sync_snapshots(self, target_dataset, show_progress=False):
         """sync our snapshots to target_dataset"""
 
-        if 'receive_resume_token' in target_dataset.properties:
-            resume_token=target_dataset.properties['receive_resume_token']
-        else:
-            resume_token=None
-
-        #determine snapshot we should start sending from
-        if not target_dataset.exists:
-            #we have nothing, so start from the first one
+        #determine start snapshot (the first snapshot after the common snapshot)
+        self.verbose("Determining start snapshot")
+        common_snapshot=self.find_common_snapshot(target_dataset)
+        if not common_snapshot:
+            #start from beginning
             start_snapshot=self.our_snapshots[0]
-        elif if not target_dataset.snapshots:
-            # we have no snapshots on target (yet?). can we resume?
-            if 'receive_resume_token' in target_dataset.properties:
-            resume_token=target_dataset.properties['receive_resume_token']
-            #no snapshots yet
-            start_snapshot=target_dataset.our_snapshots
-
-
-        #dertermine the snapshots that are obsolete so we can clean along the way.
-        (source_keeps, source_obsoletes)=self.thin()
-        #XXX: pre-create target snapshot list with exist=False so the thinner can "plan ahead" what the target eventually wants
-        (target_keeps, target_obsoletes)=self.thin()
-
-
-
-        # inital transfer
-        resume_token=None
-        if not target_dataset.exists:
-            self.debug("Sync snapshots: Initial transfer")
-            self.our_snapshots[0].transfer_snapshot(target_dataset, show_progress=show_progress)
         else:
-            #filesystem exists, need to resume something?
-            if 'receive_resume_token' in target_dataset.properties:
-                self.debug("Sync snapshots: Found resume token")
-                resume_token=target_dataset.properties['receive_resume_token']
+            start_snapshot=self.find_our_next_snapshot(common_snapshot)
 
-                #resume initial transfer?
-                if len(target_dataset.our_snapshots)==0:
-                    self.debug("Sync snapshots: Resuming inital transfer")
-                    self.our_snapshots[0].transfer_snapshot(target_dataset, show_progress=show_progress, resume_token=resume_token)
-                    resume_token=None
+        #create virtual target snapshots
+        self.verbose("Creating virtual target snapshots")
+        source_snapshot=start_snapshot
+        while source_snapshot:
+            #create virtual target snapshot
+            virtual_snapshot=ZfsDataset(target_dataset.zfs_node, target_dataset.filesystem_name+"@"+source_snapshot.snapshot_name,force_exists=False)
+            target_dataset.snapshots.append(virtual_snapshot)
+            source_snapshot=self.find_our_next_snapshot(source_snapshot)
 
-        #increments
-        self.debug("Sync snapshots: Incremental transfer")
-        latest_common_snapshot=None
-        for source_snapshot in self.our_snapshots:
-            target_snapshot=target_dataset.find_snapshot(source_snapshot.snapshot_name)
-            #already transferred
-            if target_snapshot:
-                latest_common_snapshot=source_snapshot
-            else:
-                if latest_common_snapshot:
-                    # do we still want it on target?
-                    #transfer it
-                    source_snapshot.transfer_snapshot(target_dataset, latest_common_snapshot, show_progress=True, resume_token=resume_token)
-                    resume_token=None
-                    latest_common_snapshot=source_snapshot
+        #now let thinner decide what we want on both sides
+        self.verbose("Create thinning list")
+        (source_keeps, source_obsoletes)=self.thin(keeps=[self.our_snapshots[:-1]])
+        (target_keeps, target_obsoletes)=target_dataset.thin(keeps=[target_dataset.our_snapshots[:-1]])
 
-                    #
+        #stuff that is before common snapshot can be deleted rightaway
+        if common_snapshot:
+            for source_snapshot in self.our_snapshots:
+                if source_snapshot.snapshot_name==common_snapshot.snapshot_name:
+                    break
+
+                if source_snapshot in source_obsoletes:
+                    source_snapshot.destroy()
+
+            for target_snapshot in target_dataset.our_snapshots:
+                if target_snapshot.snapshot_name==common_snapshot.snapshot_name:
+                    break
+
+                if target_snapshot in target_obsoletes:
+                    target_snapshot.destroy()
+
+        #now send/destroy the rest on the source
+        prev_source_snapshot=common_snapshot
+        source_snapshot=start_snapshot
+        while source_snapshot:
+            #does target want it?
+            if target_dataset.find_snapshot(source_snapshot.snapshot_name):
+                self.transfer_snapshot(target_dataset, show_progress=show_progress, resume_token=resume_token)
+            source_snapshot=self.find_our_next_snapshot(source_snapshot)
 
-        if not latest_common_snapshot:
-            raise(Exception("Cant find a common snapshot. (hint: zfs destroy {})".format(target_dataset)))