/// <summary>Adds the given plan to the plan cache.</summary>
/// <remarks>
/// The plan is not contained within the cache after this call, it is assumed in use by the client.
/// This call simply reserves storage and marks the plan as referenced for the LRU.
/// </remarks>
public void Add(ServerProcess process, string statement, int contextHashCode, ServerPlan plan)
{
CachedPlans bumped = null;
CachedPlanHeader header = GetPlanHeader(process, statement, contextHashCode);
plan.Header = header;
plan.PlanCacheTimeStamp = process.Catalog.PlanCacheTimeStamp;
lock (this)
{
if (_plans != null)
{
CachedPlans plans;
if (!_plans.TryGetValue(header, out plans))
{
plans = new CachedPlans();
}
bumped = _plans.Reference(header, plans);
}
}
if (bumped != null)
{
DisposeCachedPlans(process, bumped);
}
}
private void DisposeCachedPlans(ServerProcess process, CachedPlans plans)
{
foreach (ServerPlan plan in plans)
{
DisposeCachedPlan(process, plan);
}
}
/// <summary>Gets a cached plan for the given statement, if available.</summary>
/// <remarks>
/// If a plan is found, it is referenced for the LRU, and disowned by the cache.
/// The client must call Release to return the plan to the cache.
/// If no plan is found, null is returned and the cache is unaffected.
/// </remarks>
public ServerPlan Get(ServerProcess process, string statement, int contextHashCode)
{
ServerPlan plan = null;
CachedPlanHeader header = GetPlanHeader(process, statement, contextHashCode);
CachedPlans bumped = null;
lock (this)
{
if (_plans != null)
{
CachedPlans plans;
if (_plans.TryGetValue(header, out plans))
{
for (int planIndex = plans.Count - 1; planIndex >= 0; planIndex--)
{
plan = plans[planIndex];
plans.RemoveAt(planIndex);
if (process.Catalog.PlanCacheTimeStamp > plan.PlanCacheTimeStamp)
{
DisposeCachedPlan(process, plan);
plan = null;
}
else
{
bumped = _plans.Reference(header, plans);
break;
}
}
}
}
}
if (bumped != null)
{
DisposeCachedPlans(process, bumped);
}
if (plan != null)
{
plan.BindToProcess(process);
}
return(plan);
}