class CQL::Cache::RequestQueryCache

• CQL::Cache::RequestQueryCache
• Reference
• Object

Overview

Per-request query tracker: counts the SQL statements a request runs, so repeated ones (an N+1, a duplicated lookup) show up. It stores and serves no rows: #with_cache always runs its block.

Tracking is opt-in. A request is the fiber that called #start_request, until its #end_request: each request fiber has its own request id, statements and counters, so concurrent requests do not see or reset each other's. Queries run by a fiber the request spawns are not tracked (that fiber has no request). Outside a request nothing is tracked, unless tracking is turned on with enabled = true; those statements go to one process-wide tracker.

Entries are keyed by the SQL text plus a hash of the bound parameters, so no parameter values are retained, and bounded by max_size per request; the oldest entry (insertion order) is evicted first.

A request fiber that dies without #end_request leaves its entry behind until the next #start_request that finds at least SWEEP_THRESHOLD entries (or twice as many as the last sweep left, a bound that #end_request lowers again as entries go), which drops every entry whose fiber is dead.

Defined in:

cache/request_query_cache.cr

Constant Summary

SWEEP_THRESHOLD = 64

Constructors

• .instance : RequestQueryCache
• .new(max_size : Int32 = 1000)

Instance Method Summary

• #active_requests : Int32

  The number of request fibers with state: requests in flight, plus fibers that ended without calling #end_request and have not been swept yet.

• #clear : Nil

  Drops the current request's statements (outside a request, the process-wide tracker's); keeps the id.

• #current_request_id : String | Nil

  The current fiber's request id; nil outside a request.

• #enabled=(enabled : Bool) : Nil

  Explicitly enables tracking outside requests; false disables tracking entirely, including for requests that are still active.

• #enabled? : Bool

  True on a fiber with a request, or everywhere once explicitly enabled.

• #end_request : Nil

  Ends the current fiber's request; once its last #start_request is matched, drops its state.

• #get(sql : String, params : Array(DB::Any)) : Result | Nil

  Get cached result for a query.

• #mark_query_executed(sql : String, params : Array(DB::Any)) : Nil

  Records a query execution, counting a hit when it was already seen.

• #query_executed?(sql : String, params : Array(DB::Any)) : Bool

  Check if a query has been executed before in this request

• #set(sql : String, params : Array(DB::Any), result : Result) : Nil

  Store query result in cache

• #size : Int32

  Statements tracked for the current request (outside a request, by the process-wide tracker).

• #start_request(request_id : String | Nil = nil) : Nil

  Starts a request on the current fiber: clears its statements and tracks until the matching #end_request.

• #stats : Hash(String, String | Int32 | Int64 | Float64)

  Inside a request, its id, size and counters.

• #with_cache(sql : String, params : Array(DB::Any), & : -> T) : T forall T

  Simple cache tracking without result storage

Constructor Detail

Instance Method Detail