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test_consensus_render_to_dot.go
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test_consensus_render_to_dot.go
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package consensus
import (
"bytes"
"fmt"
"io"
"io/ioutil"
"os/exec"
"strings"
)
// RenderDAGToDot is a helper function for debugging tests.
// It requires graphviz installed.
func (tc *testConsensus) RenderDAGToDot(filename string) error {
dotScript, _ := tc.convertToDot()
return renderDotScript(dotScript, filename)
}
func (tc *testConsensus) convertToDot() (string, error) {
var dotScriptBuilder strings.Builder
dotScriptBuilder.WriteString("digraph {\n\trankdir = TB; \n")
edges := []string{}
blocksIterator, err := tc.blockStore.AllBlockHashesIterator(tc.databaseContext)
if err != nil {
return "", err
}
defer blocksIterator.Close()
for ok := blocksIterator.First(); ok; ok = blocksIterator.Next() {
hash, err := blocksIterator.Get()
if err != nil {
return "", err
}
dotScriptBuilder.WriteString(fmt.Sprintf("\t\"%s\";\n", hash))
parents, err := tc.dagTopologyManager.Parents(hash)
if err != nil {
return "", err
}
for _, parentHash := range parents {
edges = append(edges, fmt.Sprintf("\t\"%s\" -> \"%s\";", hash, parentHash))
}
}
dotScriptBuilder.WriteString("\n")
dotScriptBuilder.WriteString(strings.Join(edges, "\n"))
dotScriptBuilder.WriteString("\n}")
return dotScriptBuilder.String(), nil
}
func renderDotScript(dotScript string, filename string) error {
command := exec.Command("dot", "-Tsvg")
stdin, err := command.StdinPipe()
if err != nil {
return fmt.Errorf("Error creating stdin pipe: %s", err)
}
spawn("renderDotScript", func() {
defer stdin.Close()
_, err = io.WriteString(stdin, dotScript)
if err != nil {
panic(fmt.Errorf("Error writing dotScript into stdin pipe: %s", err))
}
})
var stderr bytes.Buffer
command.Stderr = &stderr
svg, err := command.Output()
if err != nil {
return fmt.Errorf("Error getting output of dot: %s\nstderr:\n%s", err, stderr.String())
}
return ioutil.WriteFile(filename, svg, 0600)
}