Gabe Black has uploaded this change for review. (
https://gem5-review.googlesource.com/10848
Change subject: systemc: Add a class which encapsulates Fibers.
......................................................................
systemc: Add a class which encapsulates Fibers.
This class encapsulates the idea of a Fiber in such a way that other
implementations can be substituted in in the future. This
implementation uses the ucontext family of functions.
This change also adds a new unit test which exercises the new class. It
creates three new fibers which accept a sequence of other fibers to
switch to, one after the other. The main test function switches to
the these fibers which switch with each other and occasionally back to
the main fiber. Each time a test fiber is activated, it checks against
a list which shows the correct order for the fibers to run in. When the
main fiber gets control, it makes sure that list has been progressed
through by the correct amount.
Change-Id: I5a42c913fa90d3fc07b9684ab30ad811695bc962
---
M src/systemc/core/SConscript
A src/systemc/core/fiber.cc
A src/systemc/core/fiber.hh
A src/systemc/core/fibertest.cc
4 files changed, 331 insertions(+), 0 deletions(-)
diff --git a/src/systemc/core/SConscript b/src/systemc/core/SConscript
index e12ed59..65c00bd 100644
--- a/src/systemc/core/SConscript
+++ b/src/systemc/core/SConscript
@@ -30,6 +30,8 @@
if env['USE_SYSTEMC']:
SimObject('SystemC.py')
+ Source('fiber.cc')
+ GTest('fibertest', 'fibertest.cc', 'fiber.cc')
Source('kernel.cc')
Source('sc_attr.cc')
diff --git a/src/systemc/core/fiber.cc b/src/systemc/core/fiber.cc
new file mode 100644
index 0000000..387eae9
--- /dev/null
+++ b/src/systemc/core/fiber.cc
@@ -0,0 +1,143 @@
+/*
+ * Copyright 2018 Google, Inc.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met: redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer;
+ * redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution;
+ * neither the name of the copyright holders nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * Authors: Gabe Black
+ */
+
+#include "systemc/core/fiber.hh"
+
+#include "base/logging.hh"
+
+using namespace std;
+
+namespace SystemC
+{
+
+namespace
+{
+
+/*
+ * The Gem5Fiber class is a special case that attaches to the currently
+ * executing context. That makes handling the "gem5" fiber, aka the one
which
+ * most of gem5 is running under, no different than other Fibers.
+ */
+class Gem5Fiber : public Fiber
+{
+ public:
+ Gem5Fiber() : Fiber(0) { started = true; }
+ void main() { panic("Gem5Fiber main executed.\n"); }
+};
+
+Gem5Fiber _gem5Fiber;
+
+// A pointer to whatever the currently executing Fiber is.
+Fiber *_currentFiber = &_gem5Fiber;
+
+// A pointer to the Fiber which is currently being started/initialized.
+Fiber *startingFiber = nullptr;
+
+} // anonymous namespace
+
+// A trampoline which calls a Fiber's enterMain() as it starts up.
+void
+Fiber::startingFiberEnterMain()
+{
+ startingFiber->enterMain();
+}
+
+Fiber::Fiber(size_t stack_size) :
+ stack(stack_size ? new uint8_t[stack_size] : nullptr),
+ stackSize(stack_size), started(false), _finished(false)
+{}
+
+Fiber::~Fiber()
+{
+ panic_if(stack && _currentFiber == this, "Fiber stack is in use.");
+ delete [] stack;
+}
+
+void
+Fiber::startFiber()
+{
+ // Set up a context for the new fiber, starting it in the trampoline.
+ getcontext(&ctx);
+ ctx.uc_stack.ss_sp = stack;
+ ctx.uc_stack.ss_size = stackSize;
+ ctx.uc_link = nullptr;
+ makecontext(&ctx, &startingFiberEnterMain, 0);
+
+ // Swap to the new context so it can enter its enterMain() function. It
+ // will then swap itself back out and return here.
+ startingFiber = this;
+ panic_if(!_currentFiber, "No active Fiber object.");
+ swapcontext(&_currentFiber->ctx, &ctx);
+
+ // The new context is now ready and about to call main().
+}
+
+void
+Fiber::enterMain()
+{
+ // Avoid a dangling pointer.
+ startingFiber = nullptr;
+
+ started = true;
+
+ // Swap back to the parent context which is still considered "current",
+ // now that we're ready to go.
+ swapcontext(&ctx, &_currentFiber->ctx);
+
+ // Call main() when we're been reactivated for the first time.
+ main();
+
+ // main has returned, so this Fiber has finished. Switch back to gem5.
+ _finished = true;
+ _gem5Fiber.run();
+}
+
+void
+Fiber::run()
+{
+ panic_if(_finished, "Fiber has already run to completion.");
+
+ // If we're already running this fiber, we're done.
+ if (_currentFiber == this)
+ return;
+
+ if (!started)
+ startFiber();
+
+ // Switch out of the current Fiber's context and this one's in.
+ Fiber *prev = _currentFiber;
+ Fiber *next = this;
+ _currentFiber = next;
+ swapcontext(&prev->ctx, &next->ctx);
+}
+
+Fiber *currentFiber() { return _currentFiber; }
+Fiber *gem5Fiber() { return &_gem5Fiber; }
+
+} // namespace SystemC
diff --git a/src/systemc/core/fiber.hh b/src/systemc/core/fiber.hh
new file mode 100644
index 0000000..dacaaf6
--- /dev/null
+++ b/src/systemc/core/fiber.hh
@@ -0,0 +1,76 @@
+/*
+ * Copyright 2018 Google, Inc.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met: redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer;
+ * redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution;
+ * neither the name of the copyright holders nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * Authors: Gabe Black
+ */
+
+#ifndef __SYSTEMC_FIBER_HH__
+#define __SYSTEMC_FIBER_HH__
+
+#include <ucontext.h>
+
+#include <cstddef>
+#include <cstdint>
+
+namespace SystemC
+{
+
+class Fiber
+{
+ protected:
+ static void startingFiberEnterMain();
+ void enterMain();
+
+ ucontext_t ctx;
+
+ // The stack for this context, or a nullptr if allocated elsewhere.
+ uint8_t *stack;
+ size_t stackSize;
+
+ bool started;
+ bool _finished;
+ void startFiber();
+ virtual void main() = 0;
+
+ public:
+ const static size_t DefaultStackSize = 0x50000;
+
+ Fiber(size_t stack_size=DefaultStackSize);
+ virtual ~Fiber();
+
+ void run();
+
+ bool finished() { return _finished; };
+};
+
+// Get a pointer to the current running Fiber.
+Fiber *currentFiber();
+// Get a pointer to the main gem5 Fiber.
+Fiber *gem5Fiber();
+
+} // namespace SystemC
+
+#endif // __SYSTEMC_FIBER_HH__
diff --git a/src/systemc/core/fibertest.cc b/src/systemc/core/fibertest.cc
new file mode 100644
index 0000000..21f7dba
--- /dev/null
+++ b/src/systemc/core/fibertest.cc
@@ -0,0 +1,110 @@
+/*
+ * Copyright 2014 Google, Inc.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met: redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer;
+ * redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution;
+ * neither the name of the copyright holders nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * Authors: Gabe Black
+ */
+
+#include <gtest/gtest.h>
+
+#include <initializer_list>
+#include <iostream>
+#include <vector>
+
+#include "systemc/core/fiber.hh"
+
+class TestFiber : public SystemC::Fiber
+{
+ public:
+ const char *name;
+ std::vector<SystemC::Fiber *> next;
+
+ TestFiber(const char *name, std::initializer_list<SystemC::Fiber *> l);
+
+ void checkExpected();
+ void main();
+};
+
+extern TestFiber a;
+extern TestFiber b;
+extern TestFiber c;
+
+TestFiber a("A", { &b, &a, SystemC::gem5Fiber(), &b, &c });
+TestFiber b("B", { &a, &c });
+TestFiber c("C", { &a, SystemC::gem5Fiber(), SystemC::gem5Fiber() });
+
+std::vector<TestFiber *>::iterator expectedIt;
+std::vector<TestFiber *> expected({
+ &a, &b, &a, &a, /* main Fiber, */
+ &a, &b, &c, &a, &c,
+ /* main Fiber, */ &c, &c
+});
+
+TestFiber::TestFiber(
+ const char *name, std::initializer_list<SystemC::Fiber *> l) :
+ name(name), next(l)
+{}
+
+void
+TestFiber::checkExpected()
+{
+ ASSERT_NE(expectedIt, expected.end());
+ TestFiber *e = *expectedIt++;
+ EXPECT_EQ(e, this) << "Expected " << e->name << ", got " << name;
+}
+
+void
+TestFiber::main()
+{
+ checkExpected();
+ for (auto &n : next) {
+ n->run();
+ checkExpected();
+ }
+}
+
+TEST(Fiber, Switching)
+{
+ expectedIt = expected.begin();
+
+ a.run();
+ EXPECT_EQ(expectedIt - expected.begin(), 4);
+
+ a.run();
+ EXPECT_EQ(expectedIt - expected.begin(), 9);
+
+ c.run();
+ EXPECT_EQ(expectedIt - expected.begin(), 10);
+
+ EXPECT_FALSE(a.finished());
+ EXPECT_FALSE(b.finished());
+ EXPECT_FALSE(c.finished());
+
+ c.run();
+ EXPECT_EQ(expected.end(), expectedIt) <<
+ "Didn't exactly use up the expected Fiber sequence";
+
+ EXPECT_TRUE(c.finished());
+}
--
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Gerrit-Project: public/gem5
Gerrit-Branch: master
Gerrit-Change-Id: I5a42c913fa90d3fc07b9684ab30ad811695bc962
Gerrit-Change-Number: 10848
Gerrit-PatchSet: 1
Gerrit-Owner: Gabe Black <gabebl...@google.com>
Gerrit-MessageType: newchange
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