The prior code used TRY...CATCH blocks to cleanup mem contexts when an error occurred. This included freeing new mem contexts that were still being initialized when the error occurred and ensuring that the prior memory context was restored.
This worked fine in production but it involved a lot of setjmp()/longjmp() calls that resulted in longer compilation times and sluggish performance under valgrind, profiling, and coverage testing.
Instead maintain a stack of new contexts and context switches that can be used to do cleanup after an error. Normally, the stack is not used for this purpose and pushing/popping is a cheap operation. In the prior implementation most of the TRY...CATCH logic needed to be run even on success.
One bonus is that the binary is about 8% smaller after this change. Another benefit is that new contexts *must* be explicitly freed/discarded or an error will occur. See info/manifest.c for an example of where this is useful outside the standard macros.
Bug Fixes:
* Prevent defunct processes in asynchronous archive commands. (Reviewed by Stephen Frost. Reported by Adam Brusselback, ejberdecia.)
* Error when archive-get/archive-push/restore are not run on a PostgreSQL host. (Reviewed by Stephen Frost. Reported by Jesper St John.)
* Read HTTP content to eof when size/encoding not specified. (Reviewed by Cynthia Shang. Reported by Christian ROUX.)
* Fix resume when the resumable backup was created by Perl. In this case the resumable backup should be ignored, but the C code was not able to load the partial manifest written by Perl since the format differs slightly. Add validations to catch this case and continue gracefully. (Reported by Kacey Holston.)
Features:
* Auto-select backup set on restore when time target is specified. Auto-selection is performed only when --set is not specified. If a backup set for the given target time cannot not be found, the latest (default) backup set will be used. (Contributed by Cynthia Shang.)
Improvements:
* Skip pg_internal.init temp file during backup. (Reviewed by Cynthia Shang. Suggested by Michael Paquier.)
* Add more validations to the manifest on backup. (Reviewed by Cynthia Shang.)
Documentation Improvements:
* Prevent lock-bot from adding comments to locked issues. (Suggested by Christoph Berg.)
If PostgreSQL crashes it can leave behind a pg_internal.init temp file with the pid as the extension, as discussed in https://www.postgresql.org/message-id/flat/20200131045352.GB2631%40paquier.xyz#7700b9481ef5b0dd5f09cc410b4750f6. On restart this file is not cleaned up so it can persist for the lifetime of the cluster or until another process with the same id happens to write pg_internal.init.
This is arguably a bug in PostgreSQL, but in any case it makes sense not to backup this file.
This error was lost during the migration to C. The error that occurred instead (generally an SSH auth error) was hard to debug.
Restore the original behavior by throwing an error immediately if pg1-host is configured for any of these commands. reset-pg1-host can be used to suppress the error when required.
The main improvement is a double-fork to prevent zombie processes if the parent process exits after the (child) async process. This is a real possibility since the parent process sticks around to monitor the results of the async process.
In the first fork, ignore SIGCHLD in the very unlikely case that the async process exits before the first fork. This is probably only possible if the async process exits immediately, perhaps due to a chdir() failure. Set SIGCHLD back to default in the async process so waitpid() will work as expected.
Also update the comment on chdir() to more accurately reflect what is happening.
Finally, add a test in certain debug builds to ensure the first fork exits very quickly. This only works when valgrind is not in use because valgrind makes forking so slow that it is hard to tell if the async process performed work or not (in the case that the second fork goes missing and the async process is a direct child).
In this case the resumable backup should be ignored, but the C code was not able to load the partial manifest written by Perl since the format differs slightly. Add validations to catch this case and continue gracefully.
Generally, the content-size or content-encoding headers will be used to specify how much content should be expected.
There is a special case where the server sends 'Connection:close' without the content headers and the content may be read up until eof.
This appears to be an atypical usage but it is required by the specification.
Auto-selection is performed only when --set is not specified. If a backup set for the given target time cannot not be found, the latest (default) backup set will be used.
Currently a limited number of date formats are recognized and timezone names are not allowed, only timezone offsets.
Validate that checksums exist for zero size files. This means that the checksums for zero size files are explicitly set by backup even though they'll always be the same. Also validate that zero length files have the correct checksum.
Validate that repo size is > 0 if size is > 0. No matter what compression type is used a non-zero amount of data cannot be stored in zero bytes.
Bug Fixes:
* Fix missing files corrupting the manifest. If a file was removed by PostgreSQL during the backup (or was missing from the standby) then the next file might not be copied and updated in the manifest. If this happened then the backup would error when restored. (Reviewed by Cynthia Shang. Reported by Vitaliy Kukharik.)
Improvements:
* Use pkg-config instead of xml2-config for libxml2 build options. (Contributed by David Steele, Adrian Vondendriesch.)
* Validate checksums are set in the manifest on backup/restore. (Reviewed by Cynthia Shang.)
This is a modest start but it addresses the specific issue that was caused by the bug fixed in 45ec694a. This validation will produce an immediate error rather than erroring out partway through the restore.
More validations are planned but this is the most important one and seems safest for this release.
If a file was removed by PostgreSQL during the backup (or was missing from the standby) then the next file might not be copied and updated in the manifest. If this happened then the backup would error when restored.
The issue was that removing files from the manifest invalidated the pointers stored in the processing queues. When a file was removed, all the pointers shifted to the next file in the list, causing a file to be unprocessed. Since the unprocessed file was still in the manifest it would be saved with no checksum, causing a failure on restore.
When process-max was > 1 then the bug would often not express since the file had already been pulled from the queue and updates to the manifest are done by name rather than by pointer.
pkg-config is a generic way to get build options rather than relying on a package-specific utility.
XML2_CONFIG can be used to override this utility for systems that do not ship pkg-config.
Bug Fixes:
* Fix error in timeline conversion. The timeline is required to verify WAL segments in the archive after a backup. The conversion was performed base 10 instead of 16, which led to errors when the timeline was ≥ 0xA. (Reported by Lukas Ertl, Eric Veldhuyzen.)
The timeline is required to verify WAL segments in the archive after a backup. The conversion was performed base 10 instead of 16, which led to errors when the timeline was ≥ 0xA.
Bug Fixes:
* Fix options being ignored by asynchronous commands. The asynchronous archive-get/archive-push processes were not loading options configured in command configuration sections, e.g. [global:archive-get]. (Reviewed by Cynthia Shang. Reported by Urs Kramer.)
* Fix handling of \ in filenames. \ was not being properly escaped when calculating the manifest checksum which prevented the manifest from loading. Since instances of \ in cluster filenames should be rare to nonexistent this does not seem likely to be a serious problem in the field.
Features:
* pgBackRest is now pure C.
* Add pg-user option. Specifies the database user name when connecting to PostgreSQL. If not specified pgBackRest will connect with the local OS user or PGUSER, which was the previous behavior. (Contributed by Mike Palmiotto.)
* Allow path-style URIs in S3 driver.
Improvements:
* The backup command is implemented entirely in C. (Reviewed by Cynthia Shang.)
The local, remote, archive-get-async, and archive-push-async commands were used to run functionality that was not directly available to the user. Unfortunately that meant they would not pick up options from the command that the user expected, e.g. backup, archive-get, etc.
Remove the internal commands and add roles which allow pgBackRest to determine what functionality is required without implementing special commands. This way the options are loaded from the expected command section.
Since remote is no longer a specific command with its own options, more manipulation is required when calling remote. This might be something we can improve in the config system but it may be worth leaving as is because it is a one-off, for now at least.
Although path-style URIs have been deprecated by AWS, they may still be used with products like Minio because no additional DNS configuration is required.
Path-style URIs must be explicitly enabled since it is not clear how they can be auto-detected reliably. More importantly, faulty detection could cause regressions in current installations.
Previously dates were not being filled by these functions which was fine since dates were not used.
We plan to use dates for the ls command plus it makes sense for the driver to be complete since it will be used as an example.
These are similar to what mktime() and strptime() do but they ignore the local system timezone which saves having to munge the TZ env variable to do time conversions.
Specifies the database user name when connecting to PostgreSQL.
If not specified pgBackRest will connect with the local OS user or PGUSER, which was the previous behavior.
\ was not being properly escaped when calculating the manifest checksum which prevented the manifest from loading.
Use jsonFromStr() to properly quote and escape \.
Since instances of \ in cluster filenames should be rare to nonexistent this does not seem likely to be a serious problem in the field.
Remove embedded Perl from the distributed binary. This includes code, configure, Makefile, and packages. The distributed binary is now pure C.
Remove storagePathEnforceSet() from the C Storage object which allowed Perl to write outside of the storage base directory. Update mock/all and real/all integration tests to use storageLocal() where they were violating this rule.
Remove "c" option that allowed the remote to tell if it was being called from C or Perl.
Code to convert options to JSON for passing to Perl (perl/config.c) has been moved to LibC since it is still required for Perl integration tests.
Update build and installation instructions in the user guide.
Remove all Perl unit tests.
Remove obsolete Perl code. In particular this included all the Perl protocol code which required modifications to the Perl storage, manifest, and db objects that are still required for integration testing but only run locally. Any remaining Perl code is required for testing, documentation, or code generation.
Rename perlReq to binReq in define.yaml to indicate that the binary is required for a test. This had been the actual meaning for quite some time but the key was never renamed.
For the most part this is a direct migration of the Perl code into C except as noted below.
A backup can now be initiated from a linked directory. The link will not be stored in the manifest or recreated on restore. If a link or directory does not already exist in the restore location then a directory will be created.
The logic for creating backup labels has been improved and it should no longer be possible to get a backup label earlier than the latest backup even with timezone changes or clock skew. This has never been an issue in the field that we know of, but we found it in testing.
For online backups all times are fetched from the PostgreSQL primary host (before only copy start was). This doesn't affect backup integrity but it does prevent clock skew between hosts affecting backup duration reporting.
Archive copy now works as expected when the archive and backup have different compression settings, i.e. when one is compressed and the other is not. This was a long-standing bug in the Perl code.
Resume will now work even if hardlink settings have been changed.
Reviewed by Cynthia Shang.
Bug Fixes:
* Fix archive-push/archive-get when PGDATA is symlinked. These commands tried to use cwd() as PGDATA but this would disagree with the path configured in pgBackRest if PGDATA was symlinked. If cwd() does not match the pgBackRest path then chdir() to the path and make sure the next cwd() matches the result from the first call. (Reported by Stephen Frost, Milosz Suchy.)
* Fix reference list when backup.info is reconstructed in expire command. Since the backup command is still using the Perl version of reconstruct this issue will not express unless 1) there is a backup missing from backup.info and 2) the expire command is run directly instead of running after backup as usual. This unlikely combination of events means this is probably not a problem in the field.
* Fix segfault on unexpected EOF in gzip decompression. (Reported by Stephen Frost.)
Commit 7168e074 tried to use cwd() as PGDATA but this would disagree with the path configured in pgBackRest if PGDATA was symlinked.
If cwd() does not match the pgBackRest path then chdir() to the path and make sure the next cwd() matches the result from the first call.
If the compressed stream terminated early then the decompression process would get a flush request (NULL input buffer) since the filter was not marked as done. This could happen on a zero-length or truncated (i.e. invalid) compressed file.
Change the existing assertion to an error to catch this condition in production gracefully.
Adding a manifest to backup.info was migrated to C in 4e4d1f41 but deduplication of the references was missed leading to a reference for every file being added to backup.info.
Since the backup command is still using the Perl version of reconstruct this issue will not express unless 1) there is a backup missing from backup.info and 2) the expire command is run directly instead of running after backup as usual.
This unlikely combination of events means this is probably not a problem in the field.
Bug Fixes:
* Fix remote timeout in delta restore. When performing a delta restore on a largely unchanged cluster the remote could timeout if no files were fetched from the repository within protocol-timeout. Add keep-alives to prevent remote timeout. (Reported by James Sewell, Jens Wilke.)
* Fix handling of repeated HTTP headers. When HTTP headers are repeated they should be considered equivalent to a single comma-separated header rather than generating an error, which was the prior behavior. (Reported by donicrosby.)
Improvements:
* JSON output from the info command is no longer pretty-printed. Monitoring systems can more easily ingest the JSON without linefeeds. External tools such as jq can be used to pretty-print if desired. (Contributed by Cynthia Shang.)
* The check command is implemented entirely in C. (Contributed by Cynthia Shang.)
Documentation Improvements:
* Document how to contribute to pgBackRest. (Contributed by Cynthia Shang.)
* Document maximum version for auto-stop option. (Contributed by Brad Nicholson.)
Test Suite Improvements:
* Fix container test path being used when --vm=none. (Suggested by Stephen Frost.)
* Fix mismatched timezone in expect test. (Suggested by Stephen Frost.)
* Don't autogenerate embedded libc code by default. (Suggested by Stephen Frost.)
When HTTP headers are repeated they should be considered equivalent to a single comma-separated header rather than generating an error, which was the prior behavior.
Reported by donicrosby.
This is only needed when new code is added to the Perl C library, which is becoming rare as the migration progresses.
Also, the code will vary slightly based on the Perl version used for generation so for normal users it is just noise.
Suggested by Stephen Frost.
When performing a delta restore on a largely unchanged cluster the remote could timeout if no files were fetched from the repository within protocol-timeout.
Add keep-alives to prevent remote timeout.
Reported by James Sewell, Jens Wilke.
