From 7302bdff8e0ca23b11784f39ffeafaea46e02212 Mon Sep 17 00:00:00 2001
From: David Thompson <david.thompson@kitware.com>
Date: Fri, 2 Jun 2023 13:02:59 -0400
Subject: [PATCH] Provide operations flexibility in what resources they lock.

---
 .../notes/operation-virtualize-locktypes.rst   | 12 ++++++++++++
 smtk/operation/Operation.cxx                   |  7 ++++++-
 smtk/operation/Operation.h                     | 18 ++++++++++++++++--
 smtk/operation/SpecificationOps.h              |  5 -----
 4 files changed, 34 insertions(+), 8 deletions(-)
 create mode 100644 doc/release/notes/operation-virtualize-locktypes.rst

diff --git a/doc/release/notes/operation-virtualize-locktypes.rst b/doc/release/notes/operation-virtualize-locktypes.rst
new file mode 100644
index 0000000000..bb5f9a7d06
--- /dev/null
+++ b/doc/release/notes/operation-virtualize-locktypes.rst
@@ -0,0 +1,12 @@
+Operation System
+----------------
+
+Operations can customize what resources they lock
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The base :smtk:`Operation <smtk::operation::Operation>` class now provides
+a virtual method, ``identifyLocksRequired()`` to allow subclasses to customize
+the default set of resources to be locked and their lock levels (read vs. write).
+This allows operations that may need to lock components related (say by
+:smtk:`Links <smtk::resource::Links>`) to external resources to include those
+resources in the operation's lock set.
diff --git a/smtk/operation/Operation.cxx b/smtk/operation/Operation.cxx
index c5df659f8c..adaa518c09 100644
--- a/smtk/operation/Operation.cxx
+++ b/smtk/operation/Operation.cxx
@@ -123,10 +123,15 @@ bool Operation::ableToOperate()
   return this->parameters()->isValid();
 }
 
+ResourceAccessMap Operation::identifyLocksRequired()
+{
+  return extractResourcesAndLockTypes(this->parameters());
+}
+
 Operation::Result Operation::operate()
 {
   // Gather all requested resources and their lock types.
-  auto resourcesAndLockTypes = extractResourcesAndLockTypes(this->parameters());
+  auto resourcesAndLockTypes = this->identifyLocksRequired();
 
   // Mutex to prevent multiple Operations from locking resources at the same
   // time (which could result in deadlock).
diff --git a/smtk/operation/Operation.h b/smtk/operation/Operation.h
index 07055cc16d..9e8becc705 100644
--- a/smtk/operation/Operation.h
+++ b/smtk/operation/Operation.h
@@ -10,11 +10,13 @@
 #ifndef smtk_operation_Operation_h
 #define smtk_operation_Operation_h
 
-#include "smtk/CoreExports.h"
+#include "smtk/resource/Lock.h"
+
 #include "smtk/PublicPointerDefs.h"
 #include "smtk/SharedFromThis.h"
 
 #include <functional>
+#include <map>
 #include <string>
 #include <typeindex>
 #include <utility>
@@ -38,6 +40,12 @@ class Operation;
 
 using Handler = std::function<void(Operation&, const std::shared_ptr<smtk::attribute::Attribute>&)>;
 
+/// Hold a set of resources to be locked for an operation along with the type of lock to acquire.
+using ResourceAccessMap = std::map<
+  std::weak_ptr<smtk::resource::Resource>,
+  smtk::resource::LockType,
+  std::owner_less<std::weak_ptr<smtk::resource::Resource>>>;
+
 /// Operation is a base class for all SMTK operations. SMTK operations are
 /// essentially functors that operate on SMTK resources and resource components.
 /// Their input parameters and output results are described by an SMTK attribute
@@ -191,7 +199,13 @@ public:
 protected:
   Operation();
 
-  // Perform the actual operation and construct the result.
+  /// Identify resources to lock, and whether to lock them for reading or writing.
+  ///
+  /// The default implementation simply calls extractResourceAndLockTypes()
+  /// on the operation's parameters.
+  virtual ResourceAccessMap identifyLocksRequired();
+
+  /// Perform the actual operation and construct the result.
   virtual Result operateInternal() = 0;
 
   // Apply post-processing to the result object. This method should not modify
diff --git a/smtk/operation/SpecificationOps.h b/smtk/operation/SpecificationOps.h
index ede605d0bc..3414c7c9bf 100644
--- a/smtk/operation/SpecificationOps.h
+++ b/smtk/operation/SpecificationOps.h
@@ -34,11 +34,6 @@ namespace operation
 /// an API around Specification, giving it functions that are unique to its role
 /// as an operation specification.
 
-typedef std::map<
-  std::weak_ptr<smtk::resource::Resource>,
-  smtk::resource::LockType,
-  std::owner_less<std::weak_ptr<smtk::resource::Resource>>>
-  ResourceAccessMap;
 typedef std::vector<smtk::attribute::ComponentItemDefinition::Ptr> ComponentDefinitionVector;
 
 /// Return a new set of parameters for an operation.
-- 
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