Implement automatic log rotation

DESCRIPTION

@@ -29,7 +29,7 @@ Suggests:
   testthat (>= 2.0.0)
 URL: https://github.com/ryapric/loggit
 BugReports: https://github.com/ryapric/loggit/issues
-RoxygenNote: 7.1.1
+RoxygenNote: 7.1.2
 Encoding: UTF-8
 Roxygen: list(markdown = TRUE)
 VignetteBuilder: knitr

NAMESPACE

@@ -1,12 +1,14 @@
 # Generated by roxygen2: do not edit by hand
 
 export(get_logfile)
+export(get_rotate_lines)
 export(get_timestamp_format)
 export(loggit)
 export(message)
 export(read_logs)
 export(rotate_logs)
 export(set_logfile)
+export(set_rotate_lines)
 export(set_timestamp_format)
 export(stop)
 export(warning)

R/configurations.R

@@ -81,3 +81,46 @@ set_timestamp_format <- function(ts_format = "%Y-%m-%dT%H:%M:%S%z", confirm = TR
 get_timestamp_format <- function() {
   .config$ts_format
 }
+
+#' Set Log File Rotation
+#'
+#' Set configuration for the number of lines after which log files are.
+#' truncated. The function will echo out the currently set line number if
+#' is set, or else it will echo that there is no limit set.
+#'
+#' This function provides a means of setting automatic log file truncation.
+#' Log files are not truncated when the value is set to `NULL`, which is
+#' also the default setting.
+#'
+#' @param rotate_lines The number of log entries to keep in the logfile.
+#'   Defaults to `NULL`, see `rotate_logs()` for implementation.
+#' @param confirm Print confirmation message of timestamp format? Defaults to
+#'   `TRUE`.
+#'
+#' @examples
+#' set_rotate_lines(100)  # set limit to 100 lines
+#' set_rotate_lines(NULL) # turn off auto-truncation
+#'
+#' @export
+set_rotate_lines <- function(rotate_lines = NULL, confirm = TRUE) {
+  .config$rotate_lines <- rotate_lines
+  if (confirm) {
+    if (is.null(rotate_lines)) {
+      print(paste0("Log file is not auto-truncated"))
+    } else {
+      print(paste0("Truncate log file after ", rotate_lines, " lines"))
+    }
+  }
+}
+
+#' Get Log File Rotation
+#'
+#' Get the configuration for the number of lines after which log files are
+#' truncated.
+#'
+#' @examples get_rotate_lines()
+#'
+#' @export
+get_rotate_lines <- function() {
+  .config$rotate_lines
+}

R/loggit.R

@@ -81,4 +81,9 @@ loggit <- function(log_lvl, log_msg, ..., echo = TRUE, custom_log_lvl = FALSE, s
   }
 
   write_ndjson(log_df, echo = echo)
+
+  # Truncate log files if needed
+  if (!is.null(get_rotate_lines())) {
+    rotate_logs(get_rotate_lines(), get_logfile())
+  }
 }

R/utils.R

@@ -80,8 +80,11 @@ read_logs <- function(logfile, unsanitizer) {
 #'
 #' @export
 rotate_logs <- function(rotate_lines = 100000, logfile) {
-  if (missing(logfile)) logfile <- get_logfile()
-  log_df <- read_logs(logfile)
-  log_df <- log_df[(nrow(log_df) - rotate_lines + 1):nrow(log_df), ]
-  write_ndjson(log_df, logfile, echo = FALSE, overwrite = TRUE)
+  if (!is.null(rotate_lines)) {
+    rotate_lines <- as.integer(rotate_lines)
+    if (missing(logfile)) logfile <- get_logfile()
+    log_df <- read_logs(logfile)
+    log_df <- log_df[max(1L, (nrow(log_df) - rotate_lines + 1)):nrow(log_df), ]
+    write_ndjson(log_df, logfile, echo = FALSE, overwrite = TRUE)
+  }
 }

R/zzz.R

@@ -1,4 +1,13 @@
 .onLoad <- function(libname, pkgname) {
   set_logfile(confirm = FALSE)
   set_timestamp_format(confirm = FALSE)
+  set_rotate_lines(NULL, confirm = FALSE)
+  invisible(NULL)
+}
+
+.onUnload <- function(libpath) {
+  for (i in names(.config)) {
+    .config[[i]] <- NULL
+  }
+  invisible(NULL)
 }

tests/testthat/test_loggit.R

@@ -39,3 +39,31 @@ test_that("Log file is returned via read_logs()", {
   expect_true("data.frame" %in% class(log_df))
 })
 cleanup()
+
+
+# ==
+
+test_that("Automatic log rotation is working", {
+
+  rotate_lines <- 10
+
+  set_rotate_lines(rotate_lines) # turn on
+  for (i in 1:(rotate_lines + 10)) {
+    loggit("INFO", paste0("log_", i), echo = FALSE)
+    log_df <- read_logs()
+    if (i <= rotate_lines) {
+      expect_true(nrow(log_df) == i)
+    } else {
+      expect_true(nrow(log_df) == rotate_lines)
+    }
+  }
+
+  set_rotate_lines(NULL) # turn off
+  for (i in 1:(rotate_lines + 10)) {
+    loggit("INFO", paste0("log_", i), echo = FALSE)
+    log_df <- read_logs()
+    expect_true(nrow(log_df) == i + rotate_lines)
+  }
+
+})
+cleanup()