SH-4492 Create a useful README for llcorehttp

Last bit for this release.  Describe stream adapters and how
to select a policy class.  Slight changes to setup code to
make reality reflect documentation.

2 files changed, 119 insertions, 16 deletions

diff --git a/indra/newview/llappcorehttp.cpp b/indra/newview/llappcorehttp.cpp
index 01317fe32f..70dcffefb2 100755
--- a/indra/newview/llappcorehttp.cpp
+++ b/indra/newview/llappcorehttp.cpp
@@ -52,6 +52,11 @@ static const struct
 } init_data[] =					//  Default and dynamic values for classes
 {
 	{
+		LLAppCoreHttp::AP_DEFAULT,			8,		8,		8,		0,
+		"",
+		"other"
+	},
+	{
 		LLAppCoreHttp::AP_TEXTURE,			8,		1,		12,		0,
 		"TextureFetchConcurrency",
 		"texture fetch"
@@ -75,6 +80,11 @@ static const struct
 		LLAppCoreHttp::AP_UPLOADS,			2,		1,		8,		0,
 		"",
 		"asset upload"
+	},
+	{
+		LLAppCoreHttp::AP_LONG_POLL,		32,		32,		32,		0,
+		"",
+		"long poll"
 	}
 };
 
@@ -154,25 +164,21 @@ void LLAppCoreHttp::init()
 	{
 		const EAppPolicy policy(init_data[i].mPolicy);
 
-		// Create a policy class but use default for texture for now.
-		// This also has the side-effect of initializing the default
-		// class to desired values.
-		if (AP_TEXTURE == policy)
+		if (AP_DEFAULT == policy)
 		{
-			mPolicies[policy] = mPolicies[AP_DEFAULT];
+			// Pre-created
+			continue;
 		}
-		else
+
+		mPolicies[policy] = LLCore::HttpRequest::createPolicyClass();
+		if (! mPolicies[policy])
 		{
-			mPolicies[policy] = LLCore::HttpRequest::createPolicyClass();
-			if (! mPolicies[policy])
-			{
-				// Use default policy (but don't accidentally modify default)
-				LL_WARNS("Init") << "Failed to create HTTP policy class for " << init_data[i].mUsage
-								 << ".  Using default policy."
-								 << LL_ENDL;
-				mPolicies[policy] = mPolicies[AP_DEFAULT];
-				continue;
-			}
+			// Use default policy (but don't accidentally modify default)
+			LL_WARNS("Init") << "Failed to create HTTP policy class for " << init_data[i].mUsage
+							 << ".  Using default policy."
+							 << LL_ENDL;
+			mPolicies[policy] = mPolicies[AP_DEFAULT];
+			continue;
 		}
 	}
 
diff --git a/indra/newview/llappcorehttp.h b/indra/newview/llappcorehttp.h
index 6dc3bb2130..40e3042b84 100755
--- a/indra/newview/llappcorehttp.h
+++ b/indra/newview/llappcorehttp.h
@@ -45,12 +45,109 @@ public:
 
 	enum EAppPolicy
 	{
+		/// Catchall policy class.  Not used yet
+		/// but will have a generous concurrency
+		/// limit.  Deep queueing possible by having
+		/// a chatty HTTP user.
+		///
+		/// Destination:     anywhere
+		/// Protocol:        http: or https:
+		/// Transfer size:   KB-MB
+		/// Long poll:       no
+		/// Concurrency:     high 
+		/// Request rate:    unknown
+		/// Pipelined:       no
 		AP_DEFAULT,
+
+		/// Texture fetching policy class.  Used to
+		/// download textures via capability or SSA
+		/// baking service.  Deep queueing of requests.
+		/// Do not share.
+		///
+		/// Destination:     simhost:12046 & bake-texture:80
+		/// Protocol:        http:
+		/// Transfer size:   KB-MB
+		/// Long poll:       no
+		/// Concurrency:     high
+		/// Request rate:    high
+		/// Pipelined:       soon
 		AP_TEXTURE,
+
+		/// Legacy mesh fetching policy class.  Used to
+		/// download textures via 'GetMesh' capability.
+		/// To be deprecated.  Do not share.
+		///
+		/// Destination:     simhost:12046
+		/// Protocol:        http:
+		/// Transfer size:   KB-MB
+		/// Long poll:       no
+		/// Concurrency:     dangerously high
+		/// Request rate:    high
+		/// Pipelined:       no
 		AP_MESH1,
+
+		/// New mesh fetching policy class.  Used to
+		/// download textures via 'GetMesh2' capability.
+		/// Used when fetch request (typically one LOD)
+		/// is 'small', currently defined as 2MB.
+		/// Very deeply queued.  Do not share.
+		///
+		/// Destination:     simhost:12046
+		/// Protocol:        http:
+		/// Transfer size:   KB-MB
+		/// Long poll:       no
+		/// Concurrency:     high
+		/// Request rate:    high
+		/// Pipelined:       soon
 		AP_MESH2,
+
+		/// Large mesh fetching policy class.  Used to
+		/// download textures via 'GetMesh' or 'GetMesh2'
+		/// capability.  Used when fetch request
+		/// is not small to avoid head-of-line problem
+		/// when large requests block a sequence of small,
+		/// fast requests.  Can be shared with similar
+		/// traffic that can wait for longish stalls
+		/// (default timeout 600S).
+		///
+		/// Destination:     simhost:12046
+		/// Protocol:        http:
+		/// Transfer size:   MB
+		/// Long poll:       no
+		/// Concurrency:     low
+		/// Request rate:    low
+		/// Pipelined:       soon
 		AP_LARGE_MESH,
+
+		/// Asset upload policy class.  Used to store
+		/// assets (mesh only at the moment) via
+		/// changeable URL.  Responses may take some
+		/// time (default timeout 240S).
+		///
+		/// Destination:     simhost:12043
+		/// Protocol:        https:
+		/// Transfer size:   KB-MB
+		/// Long poll:       no
+		/// Concurrency:     low
+		/// Request rate:    low
+		/// Pipelined:       no
 		AP_UPLOADS,
+
+		/// Long-poll-type HTTP requests.  Not
+		/// bound by a connection limit.  Requests
+		/// will typically hang around for a long
+		/// time (~30S).  Only shareable with other
+		/// long-poll requests.
+		///
+		/// Destination:     simhost:12043
+		/// Protocol:        https:
+		/// Transfer size:   KB
+		/// Long poll:       yes
+		/// Concurrency:     unlimited but low in practice
+		/// Request rate:    low
+		/// Pipelined:       no
+		AP_LONG_POLL,
+
 		AP_COUNT						// Must be last
 	};