Mimecast: change the way to consume S3 objects

[squioc]

Use generators, instead of lists, to consume the content of the S3 objects returned by the API.
The events are consumed in batch of 10000 items by default.
This behavior should fix the memory issue observed on the connector.

Summary by Sourcery

Bug Fixes:

• Fix memory issues by using generators to process S3 objects, which prevents loading large lists of events into memory at once.

[sourcery-ai]

Reviewer's Guide by Sourcery

This pull request changes the way the Mimecast connector consumes S3 objects by using generators instead of lists. This change is intended to fix memory issues observed on the connector. The events are now consumed in batches of 10000 items by default.

Sequence diagram for fetching and processing events with generators

sequenceDiagram
  participant Connector
  participant MimecastAPI
  participant S3Object
  participant EventProcessor

  Connector->>MimecastAPI: Request event URLs
  MimecastAPI-->>Connector: Returns list of S3 object URLs
  loop For each S3 object URL
    Connector->>S3Object: Download S3 object content (gzipped JSON lines)
    S3Object-->>Connector: Returns gzipped JSON lines
    Connector->>EventProcessor: Yield JSON events from lines
  end
  loop For each batch of events (size: EVENTS_BATCH_SIZE)
    Connector->>Connector: Filter events based on cursor (if applicable)
    Connector->>Connector: Increment INCOMING_MESSAGES metric
    Connector->>Connector: Yield batch of events
  end

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Updated class diagram for AsyncGeneratorConverter

classDiagram
    class AsyncGeneratorConverter {
        -async_iterator: AsyncIterator
        -loop: asyncio.BaseEventLoop
        __init__(async_generator: AsyncGenerator, loop: asyncio.BaseEventLoop)
        +__iter__()
        +get_anext() : Any
        +__next__()
    }
    note for AsyncGeneratorConverter "Converts an async generator to a synchronous iterator."

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File-Level Changes

Change	Details	Files
Refactored the download_batches function to use generators instead of lists to improve memory usage.	Modified __fetch_content, sync_download_batch, and async_download_batch to be generators. Added AsyncGeneratorConverter to convert async generators to synchronous iterables. Updated download_batches to return a generator that yields events. Added a new batched function that yields batches of items from an iterable.	Mimecast/mimecast_modules/helpers.py Mimecast/tests/test_helpers.py
Modified the event processing logic in __fetch_next_events to consume events in batches using the batched function.	Introduced EVENTS_BATCH_SIZE to control the number of events processed in each batch. Modified __fetch_next_events to use download_batches as a generator and process events in batches. The events are consumed in batch of 10000 items by default.	Mimecast/mimecast_modules/connector_mimecast_siem.py
Updated the connector version in manifest.json and added a changelog entry.	Updated the connector version to 1.1.7 in manifest.json. Added a changelog entry in CHANGELOG.md to document the fix for memory issues.	Mimecast/CHANGELOG.md Mimecast/manifest.json

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[sourcery-ai]

Hey @squioc - I've reviewed your changes - here's some feedback:

Overall Comments:

• Consider adding a more specific type hint for the iterable parameter in the batched function, e.g., Iterable[Any].
• The AsyncGeneratorConverter seems like it could be a generally useful utility - consider whether it belongs in a separate library.

Here's what I looked at during the review

• 🟢 General issues: all looks good
• 🟢 Security: all looks good
• 🟡 Testing: 4 issues found
• 🟡 Complexity: 1 issue found
• 🟢 Documentation: all looks good

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[github-actions]

Test Results

15 tests   - 45   15 ✅  - 41   1s ⏱️ - 2m 15s
 1 suites ± 0    0 💤  -  4 
 1 files   ± 0    0 ❌ ± 0 

Results for commit 55b8ecf. ± Comparison against base commit 32b1484.

This pull request removes 60 and adds 15 tests. Note that renamed tests count towards both.

tests.agents.test_init_scan ‑ test_init_scan
tests.agents.test_isolation ‑ test_endpoint_deisolation
tests.agents.test_isolation ‑ test_endpoint_isolation
tests.agents.test_isolation ‑ test_isolation_and_deisolation_actions
tests.deep_visibility.test_query ‑ test_list_remote_scripts_integration
tests.deep_visibility.test_query ‑ test_query
tests.deep_visibility.test_query ‑ test_query_canceled
tests.deep_visibility.test_query ‑ test_query_exhausted_retries
tests.deep_visibility.test_query ‑ test_query_failed
tests.iocs.test_create_iocs ‑ test_create_iocs
…

tests.test_helpers ‑ test_async_generator_converter
tests.test_helpers ‑ test_batched[abcde-2-expected1]
tests.test_helpers ‑ test_batched[abcde-3-expected0]
tests.test_helpers ‑ test_batched[iterable2-2-expected2]
tests.test_helpers ‑ test_download_batches_asynchronously
tests.test_helpers ‑ test_download_batches_synchronously
tests.test_mimecast_siem_logs ‑ test_authentication_failed
tests.test_mimecast_siem_logs ‑ test_fetch_batches
tests.test_mimecast_siem_logs ‑ test_old_cursor
tests.test_mimecast_siem_logs ‑ test_permission_denied
…

[codecov]

Codecov Report

Attention: Patch coverage is 89.13043% with 5 lines in your changes missing coverage. Please review.

Project coverage is 90.94%. Comparing base (32b1484) to head (55b8ecf).

Files with missing lines	Patch %	Lines
...mecast/mimecast_modules/connector_mimecast_siem.py	80.00%	2 Missing and 1 partial ⚠️
Mimecast/mimecast_modules/helpers.py	93.54%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1316      +/-   ##
==========================================
+ Coverage   89.83%   90.94%   +1.11%     
==========================================
  Files          77       77              
  Lines        3029     3048      +19     
  Branches      141      144       +3     
==========================================
+ Hits         2721     2772      +51     
+ Misses        257      224      -33     
- Partials       51       52       +1     

Flag	Coverage Δ
Mimecast	89.34% <89.13%> (+10.66%)	⬆️

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[squioc]

I close this PR in favor of #1318