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Subject [GitHub] [nifi-minifi-cpp] arpadboda commented on a change in pull request #590: MINIFICPP-621 Nanofi Tailfile example
Date Tue, 11 Jun 2019 23:30:49 GMT
arpadboda commented on a change in pull request #590: MINIFICPP-621 Nanofi Tailfile example
URL: https://github.com/apache/nifi-minifi-cpp/pull/590#discussion_r292697578
 
 

 ##########
 File path: nanofi/examples/tail_file.c
 ##########
 @@ -0,0 +1,270 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+    *
+    *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+*/
+
+#include "api/nanofi.h"
+#include <unistd.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <errno.h>
+#include <limits.h>
+#include <sys/stat.h>
+
+typedef struct flow_file_records {
+    flow_file_record ** records;
+    uint64_t len;
+} flow_file_records;
+
+typedef struct file_offset {
+    int offset;
+} file_offset;
+
+struct flow_file_records * flowfiles = NULL;
+struct file_offset * fileoffset = NULL;
+struct nifi_instance * instance = NULL;
+
+void transmit_flow_files(nifi_instance * instance) {
+    if (flowfiles) {
+        for (int i = 0; i < flowfiles->len; ++i) {
+            if (flowfiles->records[i]) {
+                transmit_flowfile(flowfiles->records[i], instance);
+            }
+        }
+    }
+}
+
+char * get_string(char * begin, char * end) {
+
+    if (begin == NULL || (end != NULL && end < begin)) {
+        return NULL;
+    }
+
+    int len = 0;
+    char * buff = NULL;
+
+    if (begin == end) {
+        buff = (char *)malloc(2 * sizeof(char));
+        strncpy(buff, begin, 1);
+        buff[1] = '\0';
+        return buff;
+    }
+
+    if (end) {
+        len = end - begin;
+        buff = (char *)malloc((len+1) * sizeof(char));
+        strncpy(buff, begin, len);
+        buff[len] = '\0';
+    }
+    else {
+        len = strlen(begin);
+        buff = (char *)malloc((len+1) * sizeof(char));
+        strncpy(buff, begin, len);
+        buff[len] = '\0';
+    }
+    return buff;
+}
+
+void split_string(char * str, char delim, char ** collector, int * num_strings)
+{
+    if (!str) return;
+
+    while (*str == delim) str++;
+
+    char * p = strchr(str, delim);
+    if (p) {
+        char * s = get_string(str, p);
+        if (s == NULL) {
+            return;
+        }
+        collector[*num_strings] = s;
+        (*num_strings)++;
+        split_string(p+1, delim, collector, num_strings);
+    }
+    else {
+        char * s = get_string(str, NULL);
+        if (s == NULL) {
+            return;
+        }
+        collector[*num_strings] = s;
+        (*num_strings)++;
+    }
+}
+
+void set_offset(int offset) {
+    fileoffset->offset = offset;
+}
+
+int get_offset() {
+    return fileoffset->offset;
+}
+
+void free_all_strings(char ** strings, int num_strings) {
+    for (int i = 0; i < num_strings; ++i) {
+        if (strings[i]) free(strings[i]);
+    }
+}
+
+void on_trigger_callback(processor_session * ps, processor_context * ctx) {
+
+    char file_path[50];
+    char delimiter[2];
+
+    if (get_property(ctx, "file_path", file_path, 50) != 0) {
+        return;
+    }
+
+    if (get_property(ctx, "delimiter", delimiter, 2) != 0) {
+        return;
+    }
+
+    char delim = '\0';
+    if (strlen(delimiter) > 0) {
+        delim = delimiter[0];
+    }
+
+    if (delim == '\0') {
+        printf("Invalid delimiter \n");
+        return;
+    }
+
+    if (delim == '\\') {
+      if (strlen(delimiter) > 1) {
+        switch (delimiter[1]) {
+          case 'r':
+            delim = '\r';
+            break;
+          case 't':
+            delim = '\t';
+            break;
+          case 'n':
+            delim = '\n';
+            break;
+          case '\\':
+            delim = '\\';
+            break;
+          default:
+            break;
+        }
+      }
+    }
+
+    int curr_offset = get_offset();
+    int max_bytes_read = 4096;
+    char buff[max_bytes_read];
+    FILE * fp = fopen(file_path, "rb");
+    if (!fp) return;
+    fseek(fp, curr_offset, SEEK_SET);
+    while (fgets(buff, max_bytes_read, fp) != NULL) {
+        set_offset(ftell(fp));
+        char * strings[max_bytes_read];
+        int num_strings = 0;
+        for (int i = 0; i < max_bytes_read; ++i) {
+            strings[i] = NULL;
+        }
+        split_string(buff, delim, strings, &num_strings);
+
+        flowfiles = (flow_file_records *)malloc(sizeof(flow_file_records));
+        flowfiles->records = malloc(sizeof(flow_file_record *) * num_strings);
+        flowfiles->len = num_strings;
+
+        for (int i = 0; i < num_strings; ++i) {
+            flowfiles->records[i] = NULL;
+        }
+
+        for (int i = 0; i < num_strings; ++i) {
+            flow_file_record * ffr = generate_flow_file(instance);
+            const char * flow_file = ffr->contentLocation;
+            FILE * ffp = fopen(flow_file, "wb");
+            if (!ffp) {
+                printf("Cannot open flow file at path %s to write content to.\n", flow_file);
+                fclose(fp);
+                free_all_strings(strings, num_strings);
+                return;
+            }
+            fwrite(strings[i], 1, strlen(strings[i]), ffp);
+            flowfiles->records[i] = ffr;
+            free(strings[i]);
+            fclose(ffp);
+        }
+    }
+    fclose(fp);
+}
+
+int main(int argc, char** argv) {
+
+    if (argc < 6) {
+        printf("Error: must run ./tail_file <file> <interval> <delimiter>
<nifi instance url> <remote port>\n");
+        exit(1);
+    }
+
+    char * file = argv[1];
+    char * interval = argv[2];
+    char * delimiter = argv[3];
+    char * instance_str = argv[4];
+    char * port_str = argv[5];
+
+    if (access(file, F_OK) == -1) {
+        printf("Error: %s doesn't exist!\n", file);
+        exit(1);
+    }
+
+    struct stat stats;
+    stat(file, &stats);
+
+    // Check for file existence
+    if (S_ISDIR(stats.st_mode)){
+        printf("Error: %s is a directory!\n", file);
+        exit(1);
+    }
+
+    unsigned long intrvl = strtol(interval, NULL, 10);
+
+    if (errno == ERANGE || intrvl == LONG_MAX || intrvl == LONG_MIN) {
+        printf("Invalid interval value specified\n");
+        return 0;
+    }
+
+    nifi_port port;
+
+    port.port_id = port_str;
+
+    instance = create_instance(instance_str, &port);
+
+    const char * processor_name = "TailFile";
+
+    add_custom_processor(processor_name, on_trigger_callback);
+
+    standalone_processor *standalone_proc = create_processor(processor_name);
+
+    set_standalone_property(standalone_proc, "file_path", file);
+    set_standalone_property(standalone_proc, "delimiter", delimiter);
+
+    fileoffset = (file_offset *)malloc(sizeof(file_offset));
+    set_offset(0);
+    for (;;) {
+        flow_file_record * new_ff = invoke(standalone_proc);
+        transmit_flow_files(instance);
 
 Review comment:
   👍 
   One step closer to do something useful with Nanofi! 

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