From 95cbddf19e7ddd2872f22b5e5a2d302cdfefa215 Mon Sep 17 00:00:00 2001
From: Anna Shaleva <shaleva.ann@nspcc.ru>
Date: Fri, 7 Oct 2022 15:27:24 +0300
Subject: [PATCH] cli: use custom logger to filter out runtime.Log messages

```
anna@kiwi:~/Documents/GitProjects/nspcc-dev/neo-go$ ./bin/neo-go vm -p

    _   ____________        __________      _    ____  ___
   / | / / ____/ __ \      / ____/ __ \    | |  / /  |/  /
  /  |/ / __/ / / / /_____/ / __/ / / /____| | / / /|_/ /
 / /|  / /___/ /_/ /_____/ /_/ / /_/ /_____/ |/ / /  / /
/_/ |_/_____/\____/      \____/\____/      |___/_/  /_/

NEO-GO-VM > loadgo ./1-print/1-print.go
READY: loaded 21 instructions
NEO-GO-VM 0 > run
2022-10-07T15:28:20.461+0300	INFO	runtime log	{"tx": "", "script": "db03ceb3f672ee8cd0d714989b4d103ff7eed2f3", "msg": "Hello, world!"}
[]
```
---
 cli/options/filtering_core.go      | 28 ++++++++++++++++++++++++++++
 cli/vm/cli.go                      | 21 +++++++++++++++++++--
 pkg/core/interop/runtime/engine.go |  5 ++++-
 3 files changed, 51 insertions(+), 3 deletions(-)
 create mode 100644 cli/options/filtering_core.go

diff --git a/cli/options/filtering_core.go b/cli/options/filtering_core.go
new file mode 100644
index 000000000..4dd0ad245
--- /dev/null
+++ b/cli/options/filtering_core.go
@@ -0,0 +1,28 @@
+package options
+
+import "go.uber.org/zap/zapcore"
+
+// FilteringCore is custom implementation of zapcore.Core that allows to filter
+// log entries using custom filtering function.
+type FilteringCore struct {
+	zapcore.Core
+	filter FilterFunc
+}
+
+// FilterFunc is the filter function that is called to check whether the given
+// entry together with the associated fields is to be written to a core or not.
+type FilterFunc func(zapcore.Entry) bool
+
+// NewFilteringCore returns a core middleware that uses the given filter function
+// to decide whether to log this message or not.
+func NewFilteringCore(next zapcore.Core, filter FilterFunc) zapcore.Core {
+	return &FilteringCore{next, filter}
+}
+
+// Check implements zapcore.Core interface and performs log entries filtering.
+func (c *FilteringCore) Check(e zapcore.Entry, ce *zapcore.CheckedEntry) *zapcore.CheckedEntry {
+	if c.filter(e) {
+		return c.Core.Check(e, ce)
+	}
+	return ce
+}
diff --git a/cli/vm/cli.go b/cli/vm/cli.go
index 3f5eb5e2e..1a71dcfe3 100644
--- a/cli/vm/cli.go
+++ b/cli/vm/cli.go
@@ -19,10 +19,12 @@ import (
 	"github.com/chzyer/readline"
 	"github.com/kballard/go-shellquote"
 	"github.com/nspcc-dev/neo-go/cli/flags"
+	"github.com/nspcc-dev/neo-go/cli/options"
 	"github.com/nspcc-dev/neo-go/pkg/compiler"
 	"github.com/nspcc-dev/neo-go/pkg/config"
 	"github.com/nspcc-dev/neo-go/pkg/core"
 	"github.com/nspcc-dev/neo-go/pkg/core/interop"
+	"github.com/nspcc-dev/neo-go/pkg/core/interop/runtime"
 	"github.com/nspcc-dev/neo-go/pkg/core/storage"
 	"github.com/nspcc-dev/neo-go/pkg/core/storage/dbconfig"
 	"github.com/nspcc-dev/neo-go/pkg/crypto/keys"
@@ -37,6 +39,7 @@ import (
 	"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
 	"github.com/urfave/cli"
 	"go.uber.org/zap"
+	"go.uber.org/zap/zapcore"
 )
 
 const (
@@ -392,13 +395,27 @@ func NewWithConfig(printLogotype bool, onExit func(int), c *readline.Config, cfg
 		store = storage.NewMemoryStore()
 	}
 
+	log, logCloser, err := options.HandleLoggingParams(false, cfg.ApplicationConfiguration)
+	if err != nil {
+		return nil, cli.NewExitError(fmt.Errorf("failed to init logger: %w", err), 1)
+	}
+	filter := zap.WrapCore(func(z zapcore.Core) zapcore.Core {
+		return options.NewFilteringCore(z, func(entry zapcore.Entry) bool {
+			// Log only Runtime.Notify messages.
+			return entry.Level == zapcore.InfoLevel && entry.Message == runtime.SystemRuntimeLogMessage
+		})
+	})
+	fLog := log.WithOptions(filter)
+
 	exitF := func(i int) {
 		_ = store.Close()
+		if logCloser != nil {
+			_ = logCloser()
+		}
 		onExit(i)
 	}
 
-	log := zap.NewNop()
-	chain, err := core.NewBlockchain(store, cfg.ProtocolConfiguration, log)
+	chain, err := core.NewBlockchain(store, cfg.ProtocolConfiguration, fLog)
 	if err != nil {
 		return nil, cli.NewExitError(fmt.Errorf("could not initialize blockchain: %w", err), 1)
 	}
diff --git a/pkg/core/interop/runtime/engine.go b/pkg/core/interop/runtime/engine.go
index daadcda5a..42855c10a 100644
--- a/pkg/core/interop/runtime/engine.go
+++ b/pkg/core/interop/runtime/engine.go
@@ -19,6 +19,9 @@ const (
 	MaxEventNameLen = 32
 	// MaxNotificationSize is the maximum length of a runtime log message.
 	MaxNotificationSize = 1024
+	// SystemRuntimeLogMessage represents log entry message used for output
+	// of the System.Runtime.Log syscall.
+	SystemRuntimeLogMessage = "runtime log"
 )
 
 // GetExecutingScriptHash returns executing script hash.
@@ -112,7 +115,7 @@ func Log(ic *interop.Context) error {
 	if ic.Tx != nil {
 		txHash = ic.Tx.Hash().StringLE()
 	}
-	ic.Log.Info("runtime log",
+	ic.Log.Info(SystemRuntimeLogMessage,
 		zap.String("tx", txHash),
 		zap.String("script", ic.VM.GetCurrentScriptHash().StringLE()),
 		zap.String("msg", state))