Merge pull request #46 from jhunkeler/split-delivery-code

Add multiprocessing / Split delivery code

1 files changed, 448 insertions, 0 deletions

diff --git a/src/multiprocessing.c b/src/multiprocessing.c
new file mode 100644
index 0000000..2a1b350
--- /dev/null
+++ b/src/multiprocessing.c
@@ -0,0 +1,448 @@
+#include "core.h"
+
+/// The sum of all tasks started by mp_task()
+size_t mp_global_task_count = 0;
+
+static struct MultiProcessingTask *mp_pool_next_available(struct MultiProcessingPool *pool) {
+    return &pool->task[pool->num_used];
+}
+
+int child(struct MultiProcessingPool *pool, struct MultiProcessingTask *task) {
+    FILE *fp_log = NULL;
+
+    // The task starts inside the requested working directory
+    if (chdir(task->working_dir)) {
+        perror(task->working_dir);
+        exit(1);
+    }
+
+    // Record the task start time
+    if (clock_gettime(CLOCK_REALTIME, &task->time_data.t_start) < 0) {
+        perror("clock_gettime");
+        exit(1);
+    }
+
+    // Redirect stdout and stderr to the log file
+    fflush(stdout);
+    fflush(stderr);
+    // Set log file name
+    sprintf(task->log_file + strlen(task->log_file), "task-%zu-%d.log", mp_global_task_count, task->parent_pid);
+    fp_log = freopen(task->log_file, "w+", stdout);
+    if (!fp_log) {
+        fprintf(stderr, "unable to open '%s' for writing: %s\n", task->log_file, strerror(errno));
+        return -1;
+    }
+    dup2(fileno(stdout), fileno(stderr));
+
+    // Generate timestamp for log header
+    time_t t = time(NULL);
+    char *timebuf = ctime(&t);
+    if (timebuf) {
+        // strip line feed from timestamp
+        timebuf[strlen(timebuf) ? strlen(timebuf) - 1 : 0] = 0;
+    }
+
+    // Generate log header
+    fprintf(fp_log, "# STARTED: %s\n", timebuf ? timebuf : "unknown");
+    fprintf(fp_log, "# PID: %d\n", task->parent_pid);
+    fprintf(fp_log, "# WORKDIR: %s\n", task->working_dir);
+    fprintf(fp_log, "# COMMAND:\n%s\n", task->cmd);
+    fprintf(fp_log, "# OUTPUT:\n");
+    // Commit header to log file / clean up
+    fflush(fp_log);
+
+    // Execute task
+    fflush(stdout);
+    fflush(stderr);
+    char *args[] = {"bash", "--norc", task->parent_script, (char *) NULL};
+    return execvp("/bin/bash", args);
+}
+
+int parent(struct MultiProcessingPool *pool, struct MultiProcessingTask *task, pid_t pid, int *child_status) {
+    printf("[%s:%s] Task started (pid: %d)\n", pool->ident, task->ident, pid);
+
+    // Give the child process access to our PID value
+    task->pid = pid;
+    task->parent_pid = pid;
+
+    mp_global_task_count++;
+
+    // Check child's status
+    pid_t code = waitpid(pid, child_status, WUNTRACED | WCONTINUED | WNOHANG);
+    if (code < 0) {
+        perror("waitpid failed");
+        return -1;
+    }
+    return 0;
+}
+
+static int mp_task_fork(struct MultiProcessingPool *pool, struct MultiProcessingTask *task) {
+    pid_t pid = fork();
+    int child_status = 0;
+    if (pid == -1) {
+        return -1;
+    } else if (pid == 0) {
+        child(pool, task);
+    }
+    return parent(pool, task, pid, &child_status);
+}
+
+struct MultiProcessingTask *mp_pool_task(struct MultiProcessingPool *pool, const char *ident, char *working_dir, char *cmd) {
+    struct MultiProcessingTask *slot = mp_pool_next_available(pool);
+    if (pool->num_used != pool->num_alloc) {
+        pool->num_used++;
+    } else {
+        fprintf(stderr, "Maximum number of tasks reached\n");
+        return NULL;
+    }
+
+    // Set default status to "error"
+    slot->status = -1;
+
+    // Set task identifier string
+    memset(slot->ident, 0, sizeof(slot->ident));
+    strncpy(slot->ident, ident, sizeof(slot->ident) - 1);
+
+    // Set log file path
+    memset(slot->log_file, 0, sizeof(*slot->log_file));
+    strcat(slot->log_file, pool->log_root);
+    strcat(slot->log_file, "/");
+
+    // Set working directory
+    if (isempty(working_dir)) {
+        strcpy(slot->working_dir, ".");
+    } else {
+        strncpy(slot->working_dir, working_dir, PATH_MAX - 1);
+    }
+
+    // Create a temporary file to act as our intermediate command script
+    FILE *tp = NULL;
+    char *t_name = NULL;
+    t_name = xmkstemp(&tp, "w");
+    if (!t_name || !tp) {
+        return NULL;
+    }
+
+    // Set the script's permissions so that only the calling user can use it
+    // This should help prevent eavesdropping if keys are applied in plain-text
+    // somewhere.
+    chmod(t_name, 0700);
+
+    // Record the script path
+    memset(slot->parent_script, 0, sizeof(slot->parent_script));
+    strncpy(slot->parent_script, t_name, PATH_MAX - 1);
+    guard_free(t_name);
+
+    // Populate the script
+    fprintf(tp, "#!/bin/bash\n%s\n", cmd);
+    fflush(tp);
+    fclose(tp);
+
+    // Record the command(s)
+    slot->cmd_len = (strlen(cmd) * sizeof(*cmd)) + 1;
+    slot->cmd = mmap(NULL, slot->cmd_len, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS, -1, 0);
+    memset(slot->cmd, 0, slot->cmd_len);
+    strncpy(slot->cmd, cmd, slot->cmd_len);
+
+    return slot;
+}
+
+static void get_task_duration(struct MultiProcessingTask *task, struct timespec *result) {
+    // based on the timersub() macro in time.h
+    // This implementation uses timespec and increases the resolution from microseconds to nanoseconds.
+    struct timespec *start = &task->time_data.t_start;
+    struct timespec *stop = &task->time_data.t_stop;
+    result->tv_sec = (stop->tv_sec - start->tv_sec);
+    result->tv_nsec = (stop->tv_nsec - start->tv_nsec);
+    if (result->tv_nsec < 0) {
+        --result->tv_sec;
+        result->tv_nsec += 1000000000L;
+    }
+}
+
+void mp_pool_show_summary(struct MultiProcessingPool *pool) {
+    print_banner("=", 79);
+    printf("Pool execution summary for \"%s\"\n", pool->ident);
+    print_banner("=", 79);
+    printf("STATUS     PID     DURATION     IDENT\n");
+    for (size_t i = 0; i < pool->num_used; i++) {
+        struct MultiProcessingTask *task = &pool->task[i];
+        char status_str[10] = {0};
+        if (!task->status && !task->signaled_by) {
+            strcpy(status_str, "DONE");
+        } else if (task->signaled_by) {
+            strcpy(status_str, "TERM");
+        } else {
+            strcpy(status_str, "FAIL");
+        }
+
+        struct timespec duration;
+        get_task_duration(task, &duration);
+        long diff = duration.tv_sec + duration.tv_nsec / 1000000000L;
+        printf("%-4s   %10d  %7lds     %-10s\n", status_str, task->parent_pid, diff, task->ident) ;
+    }
+    puts("");
+}
+
+static int show_log_contents(FILE *stream, struct MultiProcessingTask *task) {
+    FILE *fp = fopen(task->log_file, "r");
+    if (!fp) {
+        return -1;
+    }
+    char buf[BUFSIZ] = {0};
+    while ((fgets(buf, sizeof(buf) - 1, fp)) != NULL) {
+        fprintf(stream, "%s", buf);
+        memset(buf, 0, sizeof(buf));
+    }
+    fprintf(stream, "\n");
+    fclose(fp);
+    return 0;
+}
+
+int mp_pool_kill(struct MultiProcessingPool *pool, int signum) {
+    printf("Sending signal %d to pool '%s'\n", signum, pool->ident);
+    for (size_t i = 0; i < pool->num_used; i++) {
+        struct MultiProcessingTask *slot = &pool->task[i];
+        if (!slot) {
+            return -1;
+        }
+        // Kill tasks in progress
+        if (slot->pid > 0) {
+            int status;
+            printf("Sending signal %d to task '%s' (pid: %d)\n", signum, slot->ident, slot->pid);
+            status = kill(slot->pid, signum);
+            if (status && errno != ESRCH) {
+                fprintf(stderr, "Task '%s' (pid: %d) did not respond: %s\n", slot->ident, slot->pid, strerror(errno));
+            } else {
+                // Wait for process to handle the signal, then set the status accordingly
+                if (waitpid(slot->pid, &status, 0) >= 0) {
+                    slot->signaled_by = WTERMSIG(status);
+                    // Record the task stop time
+                    if (clock_gettime(CLOCK_REALTIME, &slot->time_data.t_stop) < 0) {
+                        perror("clock_gettime");
+                        exit(1);
+                    }
+                    // We are short-circuiting the normal flow, and the process is now dead, so mark it as such
+                    slot->pid = MP_POOL_PID_UNUSED;
+                }
+            }
+        }
+        if (!access(slot->log_file, F_OK)) {
+            remove(slot->log_file);
+        }
+        if (!access(slot->parent_script, F_OK)) {
+            remove(slot->parent_script);
+        }
+    }
+    return 0;
+}
+
+int mp_pool_join(struct MultiProcessingPool *pool, size_t jobs, size_t flags) {
+    int status = 0;
+    int failures = 0;
+    size_t tasks_complete = 0;
+    size_t lower_i = 0;
+    size_t upper_i = jobs;
+
+    do {
+        size_t hang_check = 0;
+        if (upper_i >= pool->num_used) {
+            size_t x = upper_i - pool->num_used;
+            upper_i -= (size_t) x;
+        }
+
+        for (size_t i = lower_i; i < upper_i; i++) {
+            struct MultiProcessingTask *slot = &pool->task[i];
+            if (slot->status == -1) {
+                if (mp_task_fork(pool, slot)) {
+                    fprintf(stderr, "%s: mp_task_fork failed\n", slot->ident);
+                    kill(0, SIGTERM);
+                }
+            }
+
+            // Has the child been processed already?
+            if (slot->pid == MP_POOL_PID_UNUSED) {
+                // Child is already used up, skip it
+                hang_check++;
+                if (hang_check >= pool->num_used) {
+                    // If you join a pool that's already finished it will spin
+                    // forever. This protects the program from entering an
+                    // infinite loop.
+                    fprintf(stderr, "%s is deadlocked\n", pool->ident);
+                    failures++;
+                    goto pool_deadlocked;
+                }
+                continue;
+            }
+
+            // Is the process finished?
+            pid_t pid = waitpid(slot->pid, &status, WNOHANG | WUNTRACED | WCONTINUED);
+            int task_ended = WIFEXITED(status);
+            int task_ended_by_signal = WIFSIGNALED(status);
+            int task_stopped = WIFSTOPPED(status);
+            int task_continued = WIFCONTINUED(status);
+            int status_exit = WEXITSTATUS(status);
+            int status_signal = WTERMSIG(status);
+            int status_stopped = WSTOPSIG(status);
+
+            // Update status
+            slot->status = status_exit;
+            slot->signaled_by = status_signal;
+
+            char progress[1024] = {0};
+            if (pid > 0) {
+                double percent = ((double) (tasks_complete + 1) / (double) pool->num_used) * 100;
+                snprintf(progress, sizeof(progress) - 1, "[%s:%s] [%3.1f%%]", pool->ident, slot->ident, percent);
+
+                // The process ended in one the following ways
+                // Note: SIGSTOP nor SIGCONT will not increment the tasks_complete counter
+                if (task_stopped) {
+                    printf("%s Task was suspended (%d)\n", progress, status_stopped);
+                    continue;
+                } else if (task_continued) {
+                    printf("%s Task was resumed\n", progress);
+                    continue;
+                } else if (task_ended_by_signal) {
+                    printf("%s Task ended by signal %d (%s)\n", progress, status_signal, strsignal(status_signal));
+                    tasks_complete++;
+                } else if (task_ended) {
+                    printf("%s Task ended (status: %d)\n", progress, status_exit);
+                    tasks_complete++;
+                } else {
+                    fprintf(stderr, "%s Task state is unknown (0x%04X)\n", progress, status);
+                }
+
+                // Show the log (always)
+                if (show_log_contents(stdout, slot)) {
+                    perror(slot->log_file);
+                }
+
+                // Record the task stop time
+                if (clock_gettime(CLOCK_REALTIME, &slot->time_data.t_stop) < 0) {
+                    perror("clock_gettime");
+                    exit(1);
+                }
+
+                if (status >> 8 != 0 || (status & 0xff) != 0) {
+                    fprintf(stderr, "%s Task failed\n", progress);
+                    failures++;
+
+                    if (flags & MP_POOL_FAIL_FAST && pool->num_used > 1) {
+                        mp_pool_kill(pool, SIGTERM);
+                        return -2;
+                    }
+                } else {
+                    printf("%s Task finished\n", progress);
+                }
+
+                // Clean up logs and scripts left behind by the task
+                if (remove(slot->log_file)) {
+                    fprintf(stderr, "%s Unable to remove log file: '%s': %s\n", progress, slot->parent_script, strerror(errno));
+                }
+                if (remove(slot->parent_script)) {
+                    fprintf(stderr, "%s Unable to remove temporary script '%s': %s\n", progress, slot->parent_script, strerror(errno));
+                }
+
+                // Update progress and tell the poller to ignore the PID. The process is gone.
+                slot->pid = MP_POOL_PID_UNUSED;
+            } else if (pid < 0) {
+                fprintf(stderr, "waitpid failed: %s\n", strerror(errno));
+                return -1;
+            } else {
+                // Track the number of seconds elapsed for each task.
+                // When a task has executed for longer than status_intervals, print a status update
+                // _seconds represents the time between intervals, not the total runtime of the task
+                slot->_seconds = time(NULL) - slot->_now;
+                if (slot->_seconds >  pool->status_interval) {
+                    slot->_now = time(NULL);
+                    slot->_seconds = 0;
+                }
+                if (slot->_seconds == 0) {
+                    printf("[%s:%s] Task is running (pid: %d)\n", pool->ident, slot->ident, slot->parent_pid);
+                }
+            }
+        }
+
+        if (tasks_complete == pool->num_used) {
+            break;
+        }
+
+        if (tasks_complete == upper_i) {
+            lower_i += jobs;
+            upper_i += jobs;
+        }
+
+        // Poll again after a short delay
+        sleep(1);
+    } while (1);
+
+    pool_deadlocked:
+    puts("");
+    return failures;
+}
+
+
+struct MultiProcessingPool *mp_pool_init(const char *ident, const char *log_root) {
+    struct MultiProcessingPool *pool;
+
+    if (!ident || !log_root) {
+        // Pool must have an ident string
+        // log_root must be set
+        return NULL;
+    }
+
+    // The pool is shared with children
+    pool = mmap(NULL, sizeof(*pool), PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS, -1, 0);
+
+    // Set pool identity string
+    memset(pool->ident, 0, sizeof(pool->ident));
+    strncpy(pool->ident, ident, sizeof(pool->ident) - 1);
+
+    // Set logging base directory
+    memset(pool->log_root, 0, sizeof(pool->log_root));
+    strncpy(pool->log_root, log_root, sizeof(pool->log_root) - 1);
+    pool->num_used = 0;
+    pool->num_alloc = MP_POOL_TASK_MAX;
+
+    // Create the log directory
+    if (mkdirs(log_root, 0700) < 0) {
+        if (errno != EEXIST) {
+            perror(log_root);
+            mp_pool_free(&pool);
+            return NULL;
+        }
+    }
+
+    // Task array is shared with children
+    pool->task = mmap(NULL, (pool->num_alloc + 1) * sizeof(*pool->task), PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS, -1, 0);
+    if (pool->task == MAP_FAILED) {
+        perror("mmap");
+        mp_pool_free(&pool);
+        return NULL;
+    }
+
+    return pool;
+}
+
+void mp_pool_free(struct MultiProcessingPool **pool) {
+    for (size_t i = 0; i < (*pool)->num_alloc; i++) {
+    }
+    // Unmap all pool tasks
+    if ((*pool)->task) {
+        if ((*pool)->task->cmd) {
+            if (munmap((*pool)->task->cmd, (*pool)->task->cmd_len) < 0) {
+                perror("munmap");
+            }
+        }
+        if (munmap((*pool)->task, sizeof(*(*pool)->task) * (*pool)->num_alloc) < 0) {
+            perror("munmap");
+        }
+    }
+    // Unmap the pool
+    if ((*pool)) {
+        if (munmap((*pool), sizeof(*(*pool))) < 0) {
+            perror("munmap");
+        }
+        (*pool) = NULL;
+    }
+}
\ No newline at end of file