Exception with long seqs

[msolli]

I ran into an exception while rendering a long-ish sequence of things in a PDF. I can reproduce the exception in a more minimal fashion with this code:

(let [things      (repeat 46 "foo")
      show-things (fn [x] [:paragraph x])]
  (clj-pdf.core/pdf
    [{}
     (map show-things things)]
    "doc.pdf"))

On my machine, this produces:

Execution error (ExceptionConverter) at (REPL:1).
null

The value of *e in the REPL is:

#error{:cause nil, :via [{:type com.lowagie.text.ExceptionConverter, :message nil}], :trace []}

Not much info there. But if I change the number 46 to 45, it works. I converged on these numbers by trial and error.

[yogthos]

I can reproduce the issue locally. Unfortunately, there really isn't much to go on from the stack trace, but it appears that it might be a bug in the underlying OpenPDF library.

[msolli]

Thanks, good that you could reproduce locally. It was driving me crazy.

Anyway, I was wondering about the number 46, which seemed overly arbitrary to me. Then I had a look at the PDF for the number 45. The whole page was filled. So my hypothesis now is that the 46th line is causing a new page, and that this somehow break things. I then tried some other numbers, and the number 90 gave me the same NullPointerException, but this time with a stacktrace (I have no idea why).

Observe:

(let [things      (repeat 90 {:foo "foo"})
      show-things (fn [{:keys [foo]}] [:paragraph foo])]
  (clj-pdf.core/pdf
    [{}
     (map show-things things)]
    "doc.pdf"))

Output:

Execution error (NullPointerException) at clj-pdf.core/write-header-footer-content-row (core.clj:167).
null
*e
=>
#error{:cause nil,
       :via [{:type com.lowagie.text.DocumentException,
              :message "java.lang.NullPointerException",
              :at [com.lowagie.text.pdf.PdfDocument add "PdfDocument.java" 776]}
             {:type java.lang.NullPointerException, :message nil, :at [clojure.lang.RT floatCast "RT.java" 1317]}],
       :trace [[clojure.lang.RT floatCast "RT.java" 1317]
               [clj_pdf.core$write_header_footer_content_row invokeStatic "core.clj" 167]
               [clj_pdf.core$write_header_footer_content_row invoke "core.clj" 166]
               [clj_pdf.core$table_footer_header_event$fn__135242 invoke "core.clj" 185]
               [clj_pdf.core.proxy$com.lowagie.text.pdf.PdfPageEventHelper$ff19274a onEndPage nil -1]
               [com.lowagie.text.pdf.PdfDocument newPage "PdfDocument.java" 903]
               [com.lowagie.text.pdf.PdfDocument carriageReturn "PdfDocument.java" 1282]
               [com.lowagie.text.pdf.PdfDocument add "PdfDocument.java" 558]
               [com.lowagie.text.Document add "Document.java" 302]
               [clj_pdf.core$append_to_doc invokeStatic "core.clj" 111]
               [clj_pdf.core$append_to_doc invoke "core.clj" 107]
               [clj_pdf.core$add_item invokeStatic "core.clj" 484]
               [clj_pdf.core$add_item invoke "core.clj" 481]
               [clj_pdf.core$write_doc invokeStatic "core.clj" 515]
               [clj_pdf.core$write_doc invoke "core.clj" 503]
               [clj_pdf.core$pdf invokeStatic "core.clj" 572]
               [clj_pdf.core$pdf invoke "core.clj" 560]
               [vilect.pdf.candidates$eval150334 invokeStatic "candidates.clj" 3]
               [vilect.pdf.candidates$eval150334 invoke "candidates.clj" 163]
               [clojure.lang.Compiler eval "Compiler.java" 7194]
               [clojure.lang.Compiler eval "Compiler.java" 7149]
               [clojure.core$eval invokeStatic "core.clj" 3215]
               [clojure.core$eval invoke "core.clj" 3211]
               [nrepl.middleware.interruptible_eval$evaluate$fn__33082$fn__33083 invoke "interruptible_eval.clj" 87]
               [clojure.lang.AFn applyToHelper "AFn.java" 152]
               [clojure.lang.AFn applyTo "AFn.java" 144]
               [clojure.core$apply invokeStatic "core.clj" 667]
               [clojure.core$with_bindings_STAR_ invokeStatic "core.clj" 1990]
               [clojure.core$with_bindings_STAR_ doInvoke "core.clj" 1990]
               [clojure.lang.RestFn invoke "RestFn.java" 425]
               [nrepl.middleware.interruptible_eval$evaluate$fn__33082 invoke "interruptible_eval.clj" 87]
               [clojure.main$repl$read_eval_print__9206$fn__9209 invoke "main.clj" 437]
               [clojure.main$repl$read_eval_print__9206 invoke "main.clj" 437]
               [clojure.main$repl$fn__9215 invoke "main.clj" 458]
               [clojure.main$repl invokeStatic "main.clj" 458]
               [clojure.main$repl doInvoke "main.clj" 368]
               [clojure.lang.RestFn invoke "RestFn.java" 1523]
               [nrepl.middleware.interruptible_eval$evaluate invokeStatic "interruptible_eval.clj" 84]
               [nrepl.middleware.interruptible_eval$evaluate invoke "interruptible_eval.clj" 56]
               [nrepl.middleware.interruptible_eval$interruptible_eval$fn__33115$fn__33119
                invoke
                "interruptible_eval.clj"
                152]
               [clojure.lang.AFn run "AFn.java" 22]
               [nrepl.middleware.session$session_exec$main_loop__33185$fn__33189 invoke "session.clj" 218]
               [nrepl.middleware.session$session_exec$main_loop__33185 invoke "session.clj" 217]
               [clojure.lang.AFn run "AFn.java" 22]
               [java.lang.Thread run "Thread.java" 829]]}

Line 167 of clj-pdf.core is the body of this function:

(defn write-header-footer-content-row [{:keys [table x y]} ^PdfWriter writer]
  (.writeSelectedRows ^PdfPTable table (int 0) (int -1) (float x) (float y) (.getDirectContent writer)))

Seems one or more of the locals here are nil. I put a breakpoint on the line that invokes this function and got this:

So, it seems header-content is nil. This value is ultimately passed from the table-header local in setup-doc.

Does this give some hint as to what might be wrong?