core/vm: Refactor tracing to make Tracer the main interface

This CL makes several refactors:
 - Define a Tracer interface, implementing the `CaptureState` method
 - Add the VM environment as the first argument of
   `Tracer.CaptureState`
 - Rename existing functionality `StructLogger` an make it an
   implementation of `Tracer`
 - Delete `StructLogCollector` and make `StructLogger` collect the logs
   directly
 - Change all callers to use the new `StructLogger` where necessary and
   extract logs from that.
 - Deletes the apparently obsolete and likely nonfunctional 'TraceCall'
   from the eth API.

Callers that only wish accumulated logs can use the `StructLogger`
implementation straightforwardly. Callers that wish to efficiently
capture VM traces and operate on them without excessive copying can now
implement the `Tracer` interface to receive VM state at each step and
do with it as they wish.

This CL also removes the accumulation of logs from the vm.Environment;
this was necessary as part of the refactor, but also simplifies it by
removing a responsibility that doesn't directly belong to the
Environment.

1 files changed, 6 insertions, 7 deletions

diff --git a/core/vm/logger_test.go b/core/vm/logger_test.go
index 144569865..a8c4cbc0b 100644
--- a/core/vm/logger_test.go
+++ b/core/vm/logger_test.go
@@ -54,12 +54,11 @@ func newDummyEnv(ref *dummyContractRef) *dummyEnv {
 func (d dummyEnv) GetAccount(common.Address) Account {
 	return d.ref
 }
-func (d dummyEnv) AddStructLog(StructLog) {}
 
 func TestStoreCapture(t *testing.T) {
 	var (
 		env      = NewEnv(true, false)
-		logger   = newLogger(LogConfig{Collector: env}, env)
+		logger   = NewStructLogger(nil)
 		mem      = NewMemory()
 		stack    = newstack()
 		contract = NewContract(&dummyContractRef{}, &dummyContractRef{}, new(big.Int), new(big.Int), new(big.Int))
@@ -69,7 +68,7 @@ func TestStoreCapture(t *testing.T) {
 
 	var index common.Hash
 
-	logger.captureState(0, SSTORE, new(big.Int), new(big.Int), mem, stack, contract, 0, nil)
+	logger.CaptureState(env, 0, SSTORE, new(big.Int), new(big.Int), mem, stack, contract, 0, nil)
 	if len(logger.changedValues[contract.Address()]) == 0 {
 		t.Fatalf("expected exactly 1 changed value on address %x, got %d", contract.Address(), len(logger.changedValues[contract.Address()]))
 	}
@@ -86,18 +85,18 @@ func TestStorageCapture(t *testing.T) {
 		ref      = &dummyContractRef{}
 		contract = NewContract(ref, ref, new(big.Int), new(big.Int), new(big.Int))
 		env      = newDummyEnv(ref)
-		logger   = newLogger(LogConfig{Collector: env}, env)
+		logger   = NewStructLogger(nil)
 		mem      = NewMemory()
 		stack    = newstack()
 	)
 
-	logger.captureState(0, STOP, new(big.Int), new(big.Int), mem, stack, contract, 0, nil)
+	logger.CaptureState(env, 0, STOP, new(big.Int), new(big.Int), mem, stack, contract, 0, nil)
 	if ref.calledForEach {
 		t.Error("didn't expect for each to be called")
 	}
 
-	logger = newLogger(LogConfig{Collector: env, FullStorage: true}, env)
-	logger.captureState(0, STOP, new(big.Int), new(big.Int), mem, stack, contract, 0, nil)
+	logger = NewStructLogger(&LogConfig{FullStorage: true})
+	logger.CaptureState(env, 0, STOP, new(big.Int), new(big.Int), mem, stack, contract, 0, nil)
 	if !ref.calledForEach {
 		t.Error("expected for each to be called")
 	}