private ServiceCallSite CreateCallSite(Type serviceType, CallSiteChain callSiteChain)
{
if (!_stackGuard.TryEnterOnCurrentStack())
{
return(_stackGuard.RunOnEmptyStack((type, chain) => CreateCallSite(type, chain), serviceType,
callSiteChain));
}
ServiceCallSite callSite;
try
{
//检查是否已被创建,如果已创建,则抛出异常
callSiteChain.CheckCircularDependency(serviceType);
//获取指定服务的实例对象方式
// 1.首先创建普通类型的ServiceCallSite
// 2.创建泛型类型的ServiceCallSite
// 3.如果服务类型是集合.那么将获取当前类型所有实现对象
callSite = TryCreateExact(serviceType, callSiteChain) ??
TryCreateOpenGeneric(serviceType, callSiteChain) ??
TryCreateEnumerable(serviceType, callSiteChain);
}
finally
{
callSiteChain.Remove(serviceType);
}
_callSiteCache[serviceType] = callSite;
return(callSite);
}
internal IServiceCallSite CreateCallSite(Type serviceType, CallSiteChain callSiteChain)
{
lock (_callSiteCache)
{
if (_callSiteCache.TryGetValue(serviceType, out var cachedCallSite))
{
return(cachedCallSite);
}
IServiceCallSite callSite;
try
{
callSiteChain.CheckCircularDependency(serviceType);
callSite = TryCreateExact(serviceType, callSiteChain) ??
TryCreateOpenGeneric(serviceType, callSiteChain) ??
TryCreateEnumerable(serviceType, callSiteChain);
}
finally
{
callSiteChain.Remove(serviceType);
}
_callSiteCache[serviceType] = callSite;
return(callSite);
}
}
private ServiceCallSite CreateCallSite(Type serviceType, CallSiteChain callSiteChain)
{
if (!_stackGuard.TryEnterOnCurrentStack())
{
return(_stackGuard.RunOnEmptyStack((type, chain) => CreateCallSite(type, chain), serviceType, callSiteChain));
}
// We need to lock the resolution process for a single service type at a time:
// Consider the following:
// C -> D -> A
// E -> D -> A
// Resolving C and E in parallel means that they will be modifying the callsite cache concurrently
// to add the entry for C and E, but the resolution of D and A is synchronized
// to make sure C and E both reference the same instance of the callsite.
// This is to make sure we can safely store singleton values on the callsites themselves
var callsiteLock = _callSiteLocks.GetOrAdd(serviceType, static _ => new object());
lock (callsiteLock)
{
callSiteChain.CheckCircularDependency(serviceType);
ServiceCallSite callSite = TryCreateExact(serviceType, callSiteChain) ??
TryCreateOpenGeneric(serviceType, callSiteChain) ??
TryCreateEnumerable(serviceType, callSiteChain);
return(callSite);
}
}
private ServiceCallSite CreateCallSite(Type serviceType, CallSiteChain callSiteChain)
{
if (!_stackGuard.TryEnterOnCurrentStack())
{
return(_stackGuard.RunOnEmptyStack((type, chain) => CreateCallSite(type, chain), serviceType, callSiteChain));
}
ServiceCallSite callSite;
try
{
callSiteChain.CheckCircularDependency(serviceType);
callSite = TryCreateExact(serviceType, callSiteChain) ??
TryCreateOpenGeneric(serviceType, callSiteChain) ??
TryCreateEnumerable(serviceType, callSiteChain);
}
finally
{
callSiteChain.Remove(serviceType);
}
_callSiteCache[serviceType] = callSite;
return(callSite);
}