parallel processing: put some common code in FilesystemCommand + use POSIX semaphores for STDOUT synchronization across sub-processes
#!/bin/bash
# Relational pipes
# Copyright © 2020 František Kučera (Frantovo.cz, GlobalCode.info)
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, version 3 of the License.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
# This streamlet provides a single attribute: plain text content of given PDF file. It calls the tool pdftotext.
# n.b. the plain text content must fit into memory and shell variable and command-line argument (it usually will)
. "$(dirname "$(realpath "$0")")/streamlet-common.sh"
processMessage_WAITING_FOR_OUTPUT_ATTRIBUTES_METADATA() {
send OUTPUT_ATTRIBUTE_METADATA "${outputAttributeAliases[0]-pdftotext}" "string"
send WAITING_FOR_INPUT_ATTRIBUTES
}
processMessage_WAITING_FOR_OUTPUT_ATTRIBUTES() {
value="$(pdftotext "$currentFile" - | tr -d \\f)"; # tr just removes page breaks
if [[ "x$?" == "x0" ]]; then isNull="false"; else value=""; isNull="true"; fi
send OUTPUT_ATTRIBUTE "$value" "$isNull";
send WAITING_FOR_INPUT_ATTRIBUTES;
}
initialize
processMessages