@@ -92,7 +92,6 @@ func (m *Migration) Apply(opts migrate.Options) error {
9292 log .Error (err )
9393 return err
9494 }
95- defer f .Close ()
9695 buf := bufio .NewWriter (f )
9796
9897 swapCh := make (chan Swap , 1000 )
@@ -119,7 +118,7 @@ func (m *Migration) Apply(opts migrate.Options) error {
119118 for _ , prefix := range migrationPrefixes {
120119 log .VLog (" - Adding keys in prefix %s to backup file" , prefix )
121120 cidSwapper := CidSwapper {Prefix : prefix , Store : m .dstore , SwapCh : swapCh }
122- total , err := cidSwapper .Run ( true ) // DRY RUN
121+ total , err := cidSwapper .Prepare ( ) // DRY RUN
123122 if err != nil {
124123 close (swapCh )
125124 log .Error (err )
@@ -131,17 +130,12 @@ func (m *Migration) Apply(opts migrate.Options) error {
131130 // Wait for our writing to finish before doing the flushing.
132131 <- writingDone
133132 buf .Flush ()
133+ f .Close ()
134134
135- // MIGRATION: Run the real migration.
136- for _ , prefix := range migrationPrefixes {
137- log .VLog (" - Migrating keys in prefix %s" , prefix )
138- cidSwapper := CidSwapper {Prefix : prefix , Store : m .dstore }
139- total , err := cidSwapper .Run (false ) // NOT a Dry Run
140- if err != nil {
141- log .Error (err )
142- return err
143- }
144- log .Log ("%d CIDv1 keys in %s have been migrated" , total , prefix )
135+ err = m .scanAndSwap (filepath .Join (opts .Path , backupFile ), false ) // revert=false
136+ if err != nil {
137+ log .Error (err )
138+ return err
145139 }
146140
147141 // Wrap up, we are now in repo-version 12.
@@ -187,21 +181,48 @@ func (m *Migration) Revert(opts migrate.Options) error {
187181
188182 // Open revert path for reading
189183 backupPath := filepath .Join (opts .Path , backupFile )
184+ err = m .scanAndSwap (backupPath , true ) // revert = true
185+ if err != nil {
186+ log .Error (err )
187+ return err
188+ }
189+
190+ // Wrap up the Revert. We are back at version 11.
191+ if err := repo .WriteVersion ("11" ); err != nil {
192+ log .Error ("failed to write version file" )
193+ return err
194+ }
195+
196+ log .Log ("reverted version file to version 11" )
197+
198+ // Move the backup file out of the way.
199+ err = os .Rename (backupPath , backupPath + ".reverted" )
200+ if err != nil {
201+ log .Error ("could not rename the backup file, but migration worked: %s" , err )
202+ return err
203+ }
204+ return nil
205+ }
206+
207+ // Receives a backup file which contains all the things that need to be
208+ // migrated and reads every line, performing swaps in the needed direction.
209+ func (m * Migration ) scanAndSwap (backupPath string , revert bool ) error {
190210 f , err := getBackupFile (backupPath )
191211 if err != nil {
192212 log .Error (err )
193213 return err
194214 }
215+ defer f .Close ()
195216
196- unswapCh := make (chan Swap , 1000 )
217+ swapCh := make (chan Swap , 1000 )
197218 scanner := bufio .NewScanner (f )
198219 var scannerErr error
199220
200- // This will send swap objects to the Unswapper on unswapCh as they
221+ // This will send swap objects to the swapping channel as they
201222 // are read from the backup file on disk. It will also send MFS and
202- // pinset pins for reversal.
223+ // pinset pins for reversal when doing a revert .
203224 go func () {
204- defer close (unswapCh )
225+ defer close (swapCh )
205226
206227 // Process backup file first.
207228 for scanner .Scan () {
@@ -222,60 +243,53 @@ func (m *Migration) Revert(opts migrate.Options) error {
222243 break
223244 }
224245 mhashPath := prefix .Child (dshelp .MultihashToDsKey (cid .Hash ()))
225- // This is the original swap object which is what we
226- // wanted to rebuild. Old is the old path and new is
227- // the new path and the unswapper will revert this .
246+
247+ // The swapper will move cidPath to mhashPath, and the unswapper
248+ // will do the opposite .
228249 sw := Swap {Old : cidPath , New : mhashPath }
229- unswapCh <- sw
250+ swapCh <- sw
230251 }
231252 if err := scanner .Err (); err != nil {
232253 log .Error (err )
233254 return
234255 }
235256
236- // Process MFS/pinset. We have to do this in cases the user
237- // has been running with the migration for some time and made changes to
238- // the pinset or the MFS root.
239- if err := walkPinsAndMFS (unswapCh , m .dstore ); err != nil {
240- log .Error (err )
241- return
257+ if revert {
258+ // Process MFS/pinset. We have to do this in cases the
259+ // user has been running with the migration for some
260+ // time and made changes to the pinset or the MFS
261+ // root.
262+ if err := walkPinsAndMFS (swapCh , m .dstore ); err != nil {
263+ log .Error (err )
264+ return
265+ }
242266 }
243-
244267 }()
245268
246269 // The backup file contains prefixed keys, so we do not need to set
247270 // Prefix in the CidSwapper.
248271 cidSwapper := CidSwapper {Store : m .dstore }
249- total , err := cidSwapper .Revert (unswapCh )
272+ var total uint64
273+ if revert {
274+ total , err = cidSwapper .Revert (swapCh )
275+ } else {
276+ total , err = cidSwapper .Run (swapCh )
277+ }
250278 if err != nil {
251279 log .Error (err )
252280 return err
253281 }
254- // Revert will only return after unswapCh is closed, so we know
282+
283+ // The swapper will only return after swapCh is closed, so we know
255284 // scannerErr is safe to read at this point.
256285 if scannerErr != nil {
257286 return err
258287 }
259288
260- // Wrap up the Revert. We are back at version 11.
261- log .Log ("%d multihashes reverted to CidV1s" , total )
262- if err := repo .WriteVersion ("11" ); err != nil {
263- log .Error ("failed to write version file" )
264- return err
265- }
266-
267- log .Log ("reverted version file to version 11" )
268- err = f .Close ()
269- if err != nil {
270- log .Error ("could not close backup file" )
271- return err
272- }
273-
274- // Move the backup file out of the way.
275- err = os .Rename (backupPath , backupPath + ".reverted" )
276- if err != nil {
277- log .Error ("could not rename the backup file, but migration worked: %s" , err )
278- return err
289+ if revert {
290+ log .Log ("%d multihashes swapped to CidV1s" , total )
291+ } else {
292+ log .Log ("%d CidV1s swapped to multihashes" , total )
279293 }
280294 return nil
281295}
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