[pull] master from netdata:master

[pull]

See Commits and Changes for more details.

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Created by pull[bot] (v2.0.0-alpha.1)

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Summary by Sourcery

Improve metrics cardinality calculations, context loading time during startup, and fix memory corruption in the database engine. Update the streaming thread to resize message arrays safely. Fix file descriptor leaks and correct a function name in the kickstart script.

Bug Fixes:

• Prevent memory corruption in the database engine.
• Fix file descriptor leaks.
• Correct a function name in the kickstart script.
• Prevent leading comma in Docker LABELS when IMAGE is empty.
• Fix variable scope to prevent invalid memory access.
• Delay collecting all virtual interfaces.

[sourcery-ai]

Reviewer's Guide by Sourcery

This pull request includes several improvements and fixes related to metrics cardinality, context loading, memory handling, and more.

Sequence diagram for improved context loading process

sequenceDiagram
    participant H as Host
    participant T as Thread Pool
    participant DB as SQLite DB

    H->>T: Request context load
    activate T
    Note over T: Thread local SQLite connections
    T->>DB: Open meta DB connection
    T->>DB: Open context DB connection
    T->>DB: Load context data
    DB-->>T: Return context data
    T->>H: Update host context
    deactivate T
    Note over T: Close DB connections
    Note over T: Clear thread local vars

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Class diagram for host context loading structure

classDiagram
    class host_context_load_thread {
        +uv_thread_t thread
        +RRDHOST* host
        +sqlite3* db_meta_thread
        +sqlite3* db_context_thread
        +bool busy
        +bool finished
    }

    class RRDHOST {
        +host_data
    }

    host_context_load_thread --> RRDHOST: loads context for

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State diagram for thread lifecycle in context loading

stateDiagram-v2
    [*] --> Idle
    Idle --> Busy: Thread assigned
    Busy --> Loading: Open DB connections
    Loading --> Processing: Load context data
    Processing --> Cleanup: Context loaded
    Cleanup --> Idle: Close connections
    Cleanup --> [*]: Thread finished

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File-Level Changes

Change	Details	Files
Improved context load time during startup by enabling multi-threading for context restoration.	Introduced thread-local variables for database connections to avoid contention. Added logic to distribute context loading across multiple threads. Modified cleanup routine to handle thread-local variables correctly.	src/database/sqlite/sqlite_metadata.c
Enhanced metrics cardinality calculations to provide more accurate and detailed information.	Improved counting of online and offline instances and metrics. Added calculation of ephemerality for both instances and metrics. Updated the API response to include separate ephemerality values.	src/web/api/functions/function-metrics-cardinality.c
Improved handling of database connections in context-related functions.	Used thread-local database connections for improved performance and thread safety. Replaced compiled statements with regular statements for thread safety.	src/database/sqlite/sqlite_context.c
Fixed a potential memory issue in the streaming thread message handling.	Added a spinlock to protect message resizing operations. Ensured thread safety during message queue resizing.	src/streaming/stream-thread.c

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