MDEV-38936 Proactive handling of InnoDB tablespace full condition

[FarihaIS]

Description

InnoDB write failures occur when tablespace files exceed filesystem size limits (e.g. 16TB on ext4, 2TB on ext3 - varies by filesystem). Current behavior logs errors but continues accepting transactions, causing repeated failures, user disruption, and potential data integrity issues.

Add proactive monitoring by emitting warnings when InnoDB tablespaces approach a configurable size threshold. Warnings use a tiered frequency approach to balance early notification with log spam prevention.

Key features:

• Three new system variables:
  • innodb_tablespace_size_warning_threshold (default 16TB): Maximum
    tablespace size in bytes before warnings begin
  • innodb_tablespace_size_warning_pct (default 70%): Percentage of
    threshold at which to start emitting warnings
  • innodb_tablespace_size_warning_enabled (default ON): Andon cord to
    enable/disable the warning feature
• Tiered warning frequency:
  • Below warning_pct: No warnings
  • Between warning_pct and 90%: At most twice per 10% interval with
    minimum 5% gap (e.g., 70%, 77%, 81%, 89%)
  • Above 90%: Every 1% increase (90%, 91%, 92%, etc.)
• Per-tablespace tracking with automatic reset on TRUNCATE/DROP or
  threshold changes
• Zero overhead when disabled
• Progressive warnings capped at 100%

Implementation hooks into fsp_try_extend_data_file() for O(1) size checking during tablespace extension. Adds 11 bytes per tablespace (m_last_size_warning_pct, m_last_warning_threshold, m_warning_count_in_decade) to fil_space_t structure.

Release Notes

Added proactive InnoDB tablespace size monitoring to prevent filesystem size limit failures. Three new system variables enable configurable warning thresholds with tiered warning frequency:

• innodb_tablespace_size_warning_threshold (default 16TB): Maximum size before warnings
• innodb_tablespace_size_warning_pct (default 70%): When to start warnings
• innodb_tablespace_size_warning_enabled (default ON): Feature toggle

Warnings use tiered frequency: none below threshold, at most twice per 10% between threshold and 90%, then every 1% above 90%. This provides early notification without flooding error logs.

How can this PR be tested?

Execute the innodb.tablespace_size_warning test in mysql-test-run. This commit adds a test in the innodb suite.

The test validates:

1. All three system variables are visible and have correct default values
2. Basic warning emission when tablespace exceeds configured percentage
3. Configurable warning percentage (tests both 70% and 80% thresholds)
4. Threshold set to 0 disables warnings
5. Enable/disable toggle (innodb_tablespace_size_warning_enabled)
6. TRUNCATE TABLE resets warning state

Expected warning behavior in error log:

• Below innodb_tablespace_size_warning_pct (default 70%): No warnings
• Between 70-89%: At most twice per 10% with minimum 5% gap
  Example: [Warning] InnoDB: Tablespace 'test/t1' size 7340032 bytes (70%) exceeds warning threshold of 10485760 bytes
  Example: [Warning] InnoDB: Tablespace 'test/t1' size 8388608 bytes (77%) exceeds warning threshold of 10485760 bytes
• Above 90%: Every 1% increase
  Example: [Warning] InnoDB: Tablespace 'test/t1' size 9437184 bytes (90%) exceeds warning threshold of 10485760 bytes
  Example: [Warning] InnoDB: Tablespace 'test/t1' size 9543680 bytes (91%) exceeds warning threshold of 10485760 bytes

Basing the PR against the correct MariaDB version

• This is a new feature, and the PR is based against the main branch.

Copyright

All new code of the whole pull request, including one or several files that are either new files or modified ones, are contributed under the BSD-new license. I am contributing on behalf of my employer Amazon Web Services, Inc.

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[mikegriffin]

Feature request, allow additional use cases (example, tablespace becomes larger than expected):

• Make a configurable warning percent (tablespace_size_warning_pct) so warnings can start earlier without changing the byte threshold
• Replace hard-coded 90 with a named constant (high_resolution_pct)
• No change above high_resolution_pct: print on every 1% increase
• Between tablespace_size_warning_pct and high_resolution_pct: print at most twice per 10% (example, 70%, 77%, 81%, 89%, 90%, 91%, 92%)

[FarihaIS]

@mikegriffin I have just pushed some new changes. Could you please take a look and confirm whether the new implementation addresses the additional use cases you mentioned above? Thank you!