use did/createdAt/cid prefix on written records

this means we can skip over dids we don't care about without parsing
JSON *AND* we get good lexicographic sorting of log files (which will be
useful for more complex compaction later)

directory-tailer.ts

@@ -1,4 +1,5 @@
 import { IterLines } from "./util.ts";
+import { writeLiveRecord } from "./write-live.ts";
 
 type PlcOperation = unknown;
 
@@ -36,13 +37,7 @@ export class DirectoryTailer {
       )
     );
 
-    const didplc = "did:plc:".length;
-    const prefix = entry.did.substring(didplc, didplc + 2);
-    const out = "./data/plc/live/" + prefix;
-
-    await Deno.writeTextFile(out, raw + "\n", {
-      append: true,
-    });
+    await writeLiveRecord(entry, raw);
   }
 
   async fetchExports() {

get-operations.ts

@@ -1,8 +1,28 @@
 import { TextLineStream } from "jsr:@std/streams@1/text-line-stream";
 import { ExportEntry } from "./directory-tailer.ts";
 
+import "./write-compacted.ts";
+import "./write-live.ts";
+
+const addOperations = async (
+  stream: ReadableStream<Uint8Array>,
+  did: string,
+  operations: ExportEntry[]
+) => {
+  const lines = stream
+    .pipeThrough(new TextDecoderStream())
+    .pipeThrough(new TextLineStream());
+
+  for await (const line of lines.values()) {
+    if (!line.startsWith(did)) continue;
+    const [_did, _createdAt, _cid, rawEntry] = line.split("\u001f", 4);
+    const entry = JSON.parse(rawEntry) as unknown as ExportEntry;
+    operations.push(entry);
+  }
+};
+
 export const getOperations = async (did: string) => {
-  const operations = [];
+  const operations: ExportEntry[] = [];
 
   const didplc = "did:plc:".length;
   const prefix = did.substring(didplc, didplc + 2);
@@ -14,6 +34,11 @@ export const getOperations = async (did: string) => {
     a.name < b.name ? -1 : a.name > b.name ? 1 : 0
   );
   for (const entry of compactedEntries) {
+    // TODO: if we assume that compacted files are *sorted*, we get ordering by did and createdAt,
+    // which gives us a complete op log for each did. we can store a little size prefix for a block
+    // and seek over dids we don't care about, giving us whole contiguous op logs in a compacted file.
+    // but for now we just un-zstd it and skip individual lines we don't care about the same as a live file
+
     const process = new Deno.Command("zstd", {
       args: [
         "-d",
@@ -26,31 +51,17 @@ export const getOperations = async (did: string) => {
       stderr: "piped",
     }).spawn();
 
-    const lines = process.stdout
-      .pipeThrough(new TextDecoderStream())
-      .pipeThrough(new TextLineStream());
-
-    for await (const line of lines.values()) {
-      const entry = JSON.parse(line) as unknown as ExportEntry;
-      if (entry.did !== did) continue;
-      operations.push(entry);
-    }
-
+    await addOperations(process.stdout, did, operations);
     await process.status;
   }
 
-  try {
-    const f = await Deno.open(`./data/plc/live/${prefix}`, { read: true });
-    const lines = f.readable
-      .pipeThrough(new TextDecoderStream())
-      .pipeThrough(new TextLineStream());
-    for await (const line of lines.values()) {
-      const entry = JSON.parse(line) as unknown as ExportEntry;
-      if (entry.did !== did) continue;
-      operations.push(entry);
+  for (const dir of ["compacting", "live"]) {
+    try {
+      const f = await Deno.open(`./data/plc/${dir}/${prefix}`, { read: true });
+      await addOperations(f.readable, did, operations);
+    } catch (_err) {
+      // ignore
     }
-  } catch (_err) {
-    // ignore
   }
 
   return operations;

main.ts

@@ -1,7 +1,3 @@
-import { ensureDir } from "jsr:@std/fs@1";
 import { DirectoryTailer } from "./directory-tailer.ts";
 
-await ensureDir("./data/plc/compacted");
-await ensureDir("./data/plc/live");
-
 export const tailer = new DirectoryTailer();

write-compacted.ts

@@ -0,0 +1,10 @@
+import { ensureDir } from "jsr:@std/fs@1";
+
+// TODO: automate compaction here
+// 1. take note of latest-date
+// 2. move data/plc/live/* to data/plc/compacting/*
+// 3. zstd data/plc/compacting/*
+// 4. move data/plc/compacting/*.zstd to data/plc/compacted/<date>/*.zstd
+
+await ensureDir("./data/plc/compacted");
+await ensureDir("./data/plc/compacting");

write-live.ts

@@ -0,0 +1,19 @@
+import { ensureDir } from "jsr:@std/fs@1";
+
+import { ExportEntry } from "./directory-tailer.ts";
+
+await ensureDir("./data/plc/live");
+
+export async function writeLiveRecord(entry: ExportEntry, raw: string) {
+  const didplc = "did:plc:".length;
+  const prefix = entry.did.substring(didplc, didplc + 2);
+  const out = "./data/plc/live/" + prefix;
+
+  await Deno.writeTextFile(
+    out,
+    [entry.did, entry.createdAt, entry.cid, raw].join("\u001f") + "\n",
+    {
+      append: true,
+    }
+  );
+}