lucasfang commented on code in PR #209:
URL: https://github.com/apache/paimon-cpp/pull/209#discussion_r3802506780
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include/paimon/utils/read_ahead_cache.h:
##########
@@ -162,11 +173,28 @@ class PAIMON_EXPORT ReadAheadCache {
/// on the cache configuration.
Status Init(std::vector<ByteRange>&& ranges);
- /// Read a range previously provided to Init().
+ /// Read a range previously provided to Init(), copying the cached data
+ /// directly into the given destination buffer.
+ ///
+ /// Multi-segment hits are copied into `dest` segment by segment, without
+ /// an intermediate assembled buffer.
/// @param range The byte range to read.
- /// @return The byte slice containing the requested data. If the data is
not yet cached
- /// (cache miss), the returned `ByteSlice` will have a null buffer
(`buffer == nullptr`)
- Result<ByteSlice> Read(const ByteRange& range);
+ /// @param dest Destination buffer with at least `range.length` bytes.
+ /// @return true if the range was served from the cache and `dest` was
+ /// filled; false on cache miss (`dest` is left untouched).
+ Result<bool> Read(const ByteRange& range, char* dest);
+
+ /// Start fetching the first batch of pending ranges immediately.
+ /// Init() only registers the ranges; without Warmup() the first fetch
starts
+ /// when the first Read() arrives, racing the caller's own miss fetch.
+ void Warmup();
+
+ /// Collect hit/miss counters of Read() calls and the prefetch IO
+ /// counters into the given metrics as counters named after
+ /// `ReadAheadCacheMetrics`. Only reads issued through Read() are counted
+ /// as hits/misses; prefetch fetches dispatched by the cache itself are
+ /// counted in the fetch counters instead.
+ void CollectMetrics(const std::shared_ptr<Metrics>& metrics) const;
Review Comment:
done
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