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63 lines
2.1 KiB
Markdown
63 lines
2.1 KiB
Markdown
# Redis Read Access Functions
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## Overview
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Multiple functions in `RateLimitingUtil.scala` read counter data from Redis independently. This creates potential inconsistency and code duplication.
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## Current Functions Reading Redis Counters
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### 1. `underConsumerLimits` (line ~152-159)
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- **Uses**: `EXISTS` + `GET`
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- **Returns**: Boolean (are we under limit?)
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- **Handles missing key**: Returns `true` (under limit)
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- **Purpose**: Enforcement - check if request should be allowed
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### 2. `incrementConsumerCounters` (line ~185-195)
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- **Uses**: `TTL` + (`SET` or `INCR`)
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- **Returns**: (ttl, count) as tuple
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- **Handles missing key (TTL=-2)**: Creates new key with value 1
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- **Purpose**: Tracking - increment counter after allowed request
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### 3. `ttl` (line ~208-217)
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- **Uses**: `TTL` only
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- **Returns**: Long (normalized TTL)
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- **Handles missing key (TTL=-2)**: Returns 0
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- **Purpose**: Helper - get remaining time for a period
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### 4. `getCallCounterForPeriod` (line ~223-250)
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- **Uses**: `TTL` + `GET`
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- **Returns**: ((Option[Long], Option[Long]), period)
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- **Handles missing key (TTL=-2)**: Returns (Some(0), Some(0))
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- **Purpose**: Reporting - display current usage to API consumers
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## Redis TTL Semantics
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- `-2`: Key does not exist
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- `-1`: Key exists with no expiry (shouldn't happen in our rate limiting)
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- `>0`: Seconds until key expires
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## Issues
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1. **Code duplication**: Redis interaction logic repeated across functions
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2. **Inconsistency risk**: Each function interprets Redis state independently
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3. **Multiple sources of truth**: No single canonical way to read counter state
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## Recommendation
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Refactor to have ONE canonical function that reads and normalizes counter state from Redis:
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```scala
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private def getCounterState(consumerKey: String, period: LimitCallPeriod): (Long, Long) = {
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// Single place to read and normalize Redis counter data
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// Returns (calls, ttl) with -2 handled as 0
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}
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```
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All other functions should use this single source of truth.
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## Status
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- Enforcement functions work correctly
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- Reporting improved (returns 0 instead of None for missing keys)
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- Refactoring to single read function: **Not yet implemented**
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