Restore blob granule stubs for older multiversion clients

[mengxu-oai]

Problem

Older multiversion clients resolve blob granule C functions during network setup. FoundationDB 8.0 removed those exports, so setup can fail even when the application only performs ordinary reads and writes. This follows the compatibility discussion in PR #14227.

Solution

Restore the 22 blob granule C exports required by the inspected 7.2, 7.3, and 7.4 multiversion loaders. Symbol lookup succeeds, but invoking any restored function prints its name and immediately aborts. The removed feature remains unsupported.

Use direct exports because the invocation contract is identical for every API version. Preserve the historical signatures and platform export visibility.

Strengthen the shim tests to verify the selected primary client and retry transaction errors through onError() with fresh transactions and bounded timeouts. The test passes only if a successful commit and fresh readback finish within 10 seconds. Add coverage for unmodified 7.2, 7.3, and 7.4 primary clients using the current external client.

Backport to release-8.0: PR #14239.

Testing

Passed on Linux x86_64 with Clang and warnings treated as errors:

• Built and ran fdb_c_setup_tests: 1 test case and 6 assertions passed.
• Ran fdb_c_blob_granule_fatal_exports after selecting API 730: all 22 exports were present, and every isolated invocation produced the expected diagnostic and SIGABRT.
• Ran the full fdb_c_shim_library_tests suite. The new 7.2.9, 7.3.79, and 7.4.8 primary-client cases all ran and passed network setup, a checked commit, and fresh readback with the current external client and local database use disabled. The old libraries matched their public release checksums.
• Verified the 7.3.79 primary library selection with glibc binding logs. The external copy matched the built current library.
• Ran the existing MixedApiWorkloadMultiThr.toml upgrade workload through the shim with an unmodified 7.3.79 primary, API 730, and three local server processes. The same tester process passed progress checks before and after the real server upgrade from 7.3.79 to 8.0.0, then exited cleanly. Client traces recorded selection of the old and current external libraries.

The upgrade exercise checks mixed-workload progress across the restart. It does not validate every language binding or removed feature. Direct compatibility of an older binding with 8.0 as the primary library requires separate validation.

[mengxu-oai]

@spraza can you pls take a look at this change?
I'm ok with removing the testing part from this patch and moving it to a different PR to test similar issues in upgrade

[spraza]

Mostly LGTM, thanks.

One callout is this TODO in fdb_c.h needs updating:

/*
 * TODO: delete the following "blob granule" and "tenant" related data types
 * when we are sure it's safe to do so.
 *
 * These features were always experimental and have now been removed, so probably
 * the data structures can be done away with also for the FDB 8.0.0 release.
 */

Once you do that, I can accept the PR.

Edit: looks like Michael also had a similar comment: #14239 (comment). That also talks about release notes.

[mengxu-oai]

Mostly LGTM, thanks.

One callout is this TODO in fdb_c.h needs updating:

/*
 * TODO: delete the following "blob granule" and "tenant" related data types
 * when we are sure it's safe to do so.
 *
 * These features were always experimental and have now been removed, so probably
 * the data structures can be done away with also for the FDB 8.0.0 release.
 */

Once you do that, I can accept the PR.

Edit: looks like Michael also had a similar comment: #14239 (comment). That also talks about release notes.

thanks! Fixed.

[mengxu-oai]

@spraza ptal. Thanks for your suggestions! It also resolve Michael's comments.

[spraza]

The blob granule stubs (this PR) will go as part of 8.0.1. Can you revert the 8.0.0 change here, add 8.0.1 above and basically describe the bug fix you're making? Just make sure to use the existing release note format.

[mengxu-oai]

done. ptal @spraza, thanks!

[spraza]

Thanks for fixing this

[ploxiln]

I might consider testing 7.1.59 but skipping 7.2.x which I think was not much used

[mengxu-oai]

@spraza can you help check why CI is stuck?

[foundationdb-ci]

Result of foundationdb-pr-clang-ide on Linux RHEL 9

• Commit ID: f5a0d16
• Duration 0:21:33
• Result: ✅ SUCCEEDED
• Error: N/A
• Build Log terminal output (available for 30 days)
• Build Workspace zip file of the working directory (available for 30 days)

[foundationdb-ci]

Result of foundationdb-pr-macos-m1 on macOS 14.x

• Commit ID: f5a0d16
• Duration 0:35:57
• Result: ✅ SUCCEEDED
• Error: N/A
• Build Log terminal output (available for 30 days)
• Build Workspace zip file of the working directory (available for 30 days)

[foundationdb-ci]

Result of foundationdb-pr-clang on Linux RHEL 9

• Commit ID: f5a0d16
• Duration 0:48:04
• Result: ✅ SUCCEEDED
• Error: N/A
• Build Log terminal output (available for 30 days)
• Build Workspace zip file of the working directory (available for 30 days)

[foundationdb-ci]

Result of foundationdb-pr-clang-arm on Linux RHEL 9

• Commit ID: f5a0d16
• Duration 0:48:34
• Result: ✅ SUCCEEDED
• Error: N/A
• Build Log terminal output (available for 30 days)
• Build Workspace zip file of the working directory (available for 30 days)

[foundationdb-ci]

Result of foundationdb-pr on Linux RHEL 9

• Commit ID: f5a0d16
• Duration 0:58:03
• Result: ✅ SUCCEEDED
• Error: N/A
• Build Log terminal output (available for 30 days)
• Build Workspace zip file of the working directory (available for 30 days)

[foundationdb-ci]

Result of foundationdb-pr-macos on macOS 14.x

• Commit ID: f5a0d16
• Duration 1:12:45
• Result: ❌ FAILED
• Error: Error while executing command: ssh -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null -i ${HOME}/.ssh_key ec2-user@${MAC_EC2_HOST} /usr/local/bin/bash --login ./build_pr_macos.sh. Reason: exit status 8
• Build Log terminal output (available for 30 days)
• Build Workspace zip file of the working directory (available for 30 days)

[foundationdb-ci]

Result of foundationdb-pr-cluster-tests on Linux RHEL 9

• Commit ID: f5a0d16
• Duration 1:43:54
• Result: ✅ SUCCEEDED
• Error: N/A
• Build Log terminal output (available for 30 days)
• Build Workspace zip file of the working directory (available for 30 days)
• Cluster Test Logs zip file of the test logs (available for 30 days)