jschoubben
b37ed85559
The node-engine hands each process the fingerprint of the want it applies (design 47, The fingerprint handover; mesh-host W13.1). process.OwnBuild reads it once at the first ask, which Connect and Dial make before they dial, and says it in the journal; with none, or one that is no single word, it says "own build unknown" and why. Builds: design 47 G §201, §205, §239 Claude-Session: https://claude.ai/code/session_01JG73KEq4zoDfM9WtYpcQgZ
63 lines
2.3 KiB
Go
63 lines
2.3 KiB
Go
package process
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import (
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"fmt"
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"log"
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"os"
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"strings"
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"sync"
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)
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// FingerprintEnv is the environment value the node-engine starts each process with, a service and a container alike:
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// the fingerprint of the want it applies (novox/hq ADR 0656; design 47 *The fingerprint handover*).
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const FingerprintEnv = "MESH_FINGERPRINT"
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// OwnBuildUnknown is what a process started with no fingerprint says of its own build, in its journal and to whoever
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// reads it (the node-engine's process builds, the indexer acting on it as ADR 0639 §8 has it).
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const OwnBuildUnknown = "own build unknown"
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// Build is the build a process was started with: its fingerprint, or why it is unknown.
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type Build struct {
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Fingerprint string `json:"fingerprint,omitempty"`
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// Unknown says why there is no fingerprint, starting with OwnBuildUnknown; empty when there is one.
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Unknown string `json:"unknown,omitempty"`
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}
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// String is the fingerprint, or why the build is unknown.
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func (b Build) String() string {
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if b.Fingerprint != "" {
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return b.Fingerprint
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}
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return b.Unknown
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}
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// ReadOwnBuild is the build getenv's FingerprintEnv names: one word, or unknown with the reason.
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func ReadOwnBuild(getenv func(string) string) Build {
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fp := strings.TrimSpace(getenv(FingerprintEnv))
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switch {
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case fp == "":
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return Build{Unknown: OwnBuildUnknown + ": started without " + FingerprintEnv}
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case strings.ContainsAny(fp, " \t\r\n"):
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return Build{Unknown: fmt.Sprintf("%s: %s %q is not one fingerprint", OwnBuildUnknown, FingerprintEnv, fp)}
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}
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return Build{Fingerprint: fp}
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}
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// sayOwnBuild writes the process's own build in its journal; a variable so a test reads what it says.
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var sayOwnBuild = func(b Build) { log.Printf("own build: %s", b) }
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// readAndSay reads the build from this process's environment and says it.
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func readAndSay() Build {
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b := ReadOwnBuild(os.Getenv)
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sayOwnBuild(b)
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return b
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}
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// ownBuild is read once; a test that reads it makes it again (sync.OnceValue(readAndSay)) and puts it back.
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var ownBuild = sync.OnceValue(readAndSay)
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// OwnBuild is this process's own build, read once from its environment at the first ask and said in its journal then;
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// every later ask answers the same, whatever the environment says since. Connect and Dial ask it, so every process
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// that reaches the bus says it at its start.
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func OwnBuild() Build { return ownBuild() }
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