source("boot.R")
box_use(./core/laurent2)
box_use(./core/lkb)
library(DBI); library(RPostgres)
PSQL <- function(query) {
  con <- dbConnect(RPostgres::Postgres(), host=Sys.getenv("PGHOST", "100.79.14.103"),
    dbname="research_stack", user="kaleidoscope", password="kaleidoscope")
  on.exit(dbDisconnect(con))
  dbGetQuery(con, query)
}
cat(sprintf("[%s] neon worker starting (PID %d)\n", Sys.time(), Sys.getpid()), flush = TRUE)
n_jobs <- 0L
repeat {
  result <- tryCatch({
    PSQL("UPDATE lkb.compute_queue c SET status = 'running', started_at = NOW()
WHERE c.equation_id = (SELECT equation_id FROM lkb.compute_queue
  WHERE status = 'pending' ORDER BY word_length ASC NULLS LAST LIMIT 1
  FOR UPDATE SKIP LOCKED)
RETURNING c.equation_id, c.n, c.braid_word, c.word_length")
  }, error = function(e) data.frame())
  if (nrow(result) == 0) break
  eq_id <- result$equation_id[1]
  n <- result$n[1]
  word_str <- result$braid_word[1]
  word_len <- if (is.na(result$word_length[1])) 0L else result$word_length[1]
  N <- n * (n - 1) / 2L
  cat(sprintf("  [%s] B%d word, %d gens (N=%d)\n", eq_id, n, word_len, N), flush = TRUE)
  t0 <- Sys.time()
  tryCatch({
    if (word_str == "ID" || is.na(word_str) || word_str == "") {
      entry <- "1"
    } else {
      steps <- as.integer(strsplit(word_str, ",")[[1]])
      gens <- lkb$lkb_generators(n)
      mat <- laurent2$l2_mat_identity(N)
      for (g in steps) mat <- laurent2$l2_mat_mul(mat, gens[[g]])
      entry <- laurent2$l2_str(mat[[1, 3]])
    }
    esc <- gsub("'", "''", entry)
    PSQL(sprintf("UPDATE lkb.compute_queue SET status = 'done', result_entry = '%s',
      finished_at = NOW(), steps_done = %d WHERE equation_id = '%s'",
      esc, word_len, eq_id))
    cat(sprintf("  [%s] done in %.1f s (%d total)\n", eq_id,
      difftime(Sys.time(), t0, units="secs"), n_jobs + 1), flush = TRUE)
    n_jobs <- n_jobs + 1L
  }, error = function(e) {
    cat(sprintf("  [%s] ERROR: %s\n", eq_id, conditionMessage(e)), flush = TRUE)
  })
}
cat(sprintf("[%s] worker finished -- %d jobs total\n", Sys.time(), n_jobs), flush = TRUE)