fix: prevent memory leak in IOReportIterator by releasing delta CFDictionaryRef (#104)

The IOReportIterator was not releasing the delta CFDictionaryRef that was
passed to it from get_sample(). Each API call created a new delta dictionary
via IOReportCreateSamplesDelta() but it was never released, causing memory
to grow at ~300KB/second during continuous API queries.

Changes:
- Add `sample` field to IOReportIterator to store the CFDictionaryRef
- Implement Drop trait to call CFRelease on the sample when iterator is dropped
- Add memory leak test script for future regression testing

Test results (3 minutes, ~1,225 queries):
- Before: +53,472 KB memory increase
- After:  +288 KB memory increase (99.5% reduction)

Author: inureyes

src/device/macos_native/ioreport.rs

@@ -475,15 +475,36 @@ impl IOReportChannelItem {
 }
 
 /// Iterator over IOReport sample channels
+///
+/// This struct takes ownership of the sample CFDictionaryRef and releases it
+/// when the iterator is dropped, preventing memory leaks.
 pub struct IOReportIterator {
+    /// The sample CFDictionary that owns the channel data.
+    /// Must be released when the iterator is dropped.
+    sample: CFDictionaryRef,
     channels: Vec<CFDictionaryRef>,
     index: usize,
 }
 
 impl IOReportIterator {
     fn new(sample: CFDictionaryRef) -> Self {
         let channels = get_io_channels(sample);
-        Self { channels, index: 0 }
+        Self {
+            sample,
+            channels,
+            index: 0,
+        }
+    }
+}
+
+impl Drop for IOReportIterator {
+    fn drop(&mut self) {
+        // Release the sample dictionary to prevent memory leaks
+        if !self.sample.is_null() {
+            unsafe {
+                CFRelease(self.sample as *const c_void);
+            }
+        }
     }
 }
 

tests/memory-leak-test.sh

@@ -0,0 +1,138 @@
+#!/bin/bash
+
+# Memory Leak Test Script for all-smi API mode
+#
+# This script monitors memory usage while repeatedly querying the API endpoint.
+# It helps detect memory leaks by tracking RSS growth over time.
+#
+# Usage:
+#   ./tests/memory-leak-test.sh [PORT] [DURATION_SECONDS]
+#
+# Example:
+#   ./target/release/all-smi api --port 19090 &
+#   ./tests/memory-leak-test.sh 19090 60
+
+PORT=${1:-19090}
+DURATION=${2:-60}
+QUERY_INTERVAL=0.1
+MONITOR_INTERVAL=1
+
+PID=$(pgrep -f "all-smi api" | head -1)
+
+if [ -z "$PID" ]; then
+    echo "Error: all-smi api process not found"
+    echo "Please start all-smi in API mode first:"
+    echo "  ./target/release/all-smi api --port $PORT &"
+    exit 1
+fi
+
+echo "=========================================="
+echo "Memory Leak Test for all-smi API mode"
+echo "=========================================="
+echo "PID: $PID"
+echo "Port: $PORT"
+echo "Duration: ${DURATION}s"
+echo "=========================================="
+
+MEMORY_LOG=$(mktemp)
+QUERY_LOG=$(mktemp)
+
+INITIAL_RSS=$(ps -o rss= -p $PID | tr -d ' ')
+echo "Initial RSS: ${INITIAL_RSS} KB"
+echo ""
+
+# Memory monitoring
+(
+    START_TIME=$(date +%s)
+    while true; do
+        CURRENT_TIME=$(date +%s)
+        ELAPSED=$((CURRENT_TIME - START_TIME))
+        [ $ELAPSED -ge $DURATION ] && break
+        RSS=$(ps -o rss= -p $PID 2>/dev/null | tr -d ' ')
+        [ -n "$RSS" ] && echo "$ELAPSED $RSS" >> "$MEMORY_LOG"
+        sleep $MONITOR_INTERVAL
+    done
+) &
+MONITOR_PID=$!
+
+# Query loop
+(
+    QUERY_COUNT=0
+    START_TIME=$(date +%s)
+    while true; do
+        CURRENT_TIME=$(date +%s)
+        ELAPSED=$((CURRENT_TIME - START_TIME))
+        [ $ELAPSED -ge $DURATION ] && break
+        curl -s "http://localhost:$PORT/metrics" > /dev/null 2>&1
+        QUERY_COUNT=$((QUERY_COUNT + 1))
+        [ $((QUERY_COUNT % 100)) -eq 0 ] && echo "Queries: $QUERY_COUNT, Elapsed: ${ELAPSED}s" >> "$QUERY_LOG"
+        sleep $QUERY_INTERVAL
+    done
+    echo "Total queries: $QUERY_COUNT" >> "$QUERY_LOG"
+) &
+QUERY_PID=$!
+
+echo "Running test..."
+for i in $(seq 1 $DURATION); do
+    sleep 1
+    RSS=$(ps -o rss= -p $PID 2>/dev/null | tr -d ' ')
+    [ -n "$RSS" ] && printf "\r[%3d/%3ds] RSS: %d KB (D %+d KB)" $i $DURATION $RSS $((RSS - INITIAL_RSS))
+done
+echo ""
+echo ""
+
+wait $MONITOR_PID 2>/dev/null
+wait $QUERY_PID 2>/dev/null
+
+FINAL_RSS=$(ps -o rss= -p $PID | tr -d ' ')
+
+echo "=========================================="
+echo "Test Results"
+echo "=========================================="
+echo "Initial RSS: ${INITIAL_RSS} KB"
+echo "Final RSS:   ${FINAL_RSS} KB"
+echo "Difference:  $((FINAL_RSS - INITIAL_RSS)) KB"
+echo ""
+
+if [ -f "$MEMORY_LOG" ]; then
+    MIN_RSS=$(awk '{print $2}' "$MEMORY_LOG" | sort -n | head -1)
+    MAX_RSS=$(awk '{print $2}' "$MEMORY_LOG" | sort -n | tail -1)
+    AVG_RSS=$(awk '{sum+=$2; count++} END {printf "%.0f", sum/count}' "$MEMORY_LOG")
+    echo "Statistics:"
+    echo "  Min RSS: ${MIN_RSS} KB"
+    echo "  Max RSS: ${MAX_RSS} KB"
+    echo "  Avg RSS: ${AVG_RSS} KB"
+    echo "  Range:   $((MAX_RSS - MIN_RSS)) KB"
+    echo ""
+fi
+
+cat "$QUERY_LOG"
+echo ""
+
+FIRST_AVG=$(head -5 "$MEMORY_LOG" | awk '{sum+=$2; count++} END {printf "%.0f", sum/count}')
+LAST_AVG=$(tail -5 "$MEMORY_LOG" | awk '{sum+=$2; count++} END {printf "%.0f", sum/count}')
+TREND=$((LAST_AVG - FIRST_AVG))
+
+echo "=========================================="
+echo "Trend Analysis"
+echo "=========================================="
+echo "First 5 samples avg: ${FIRST_AVG} KB"
+echo "Last 5 samples avg:  ${LAST_AVG} KB"
+echo "Trend:               ${TREND} KB"
+echo ""
+
+if [ $TREND -gt 1000 ]; then
+    echo "WARNING: Memory appears to be increasing significantly!"
+    echo "This could indicate a memory leak."
+    EXIT_CODE=1
+elif [ $TREND -gt 100 ]; then
+    echo "NOTICE: Memory shows some increase."
+    echo "Consider running a longer test to confirm stability."
+    EXIT_CODE=0
+else
+    echo "Memory appears stable."
+    EXIT_CODE=0
+fi
+
+rm -f "$MEMORY_LOG" "$QUERY_LOG"
+exit $EXIT_CODE