[chore][pkg/stanza] Remove unlimited memory for file paths (#28491)

.chloggen/pkg-stanza-rm-seen-paths.yaml

@@ -0,0 +1,34 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: breaking
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: filelogreceiver
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Change "Started watching file" log behavior
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [28491]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext: |
+  Previously, every unique file path which was found by the receiver would be remembered indefinitely.
+  This list was kept independently of the uniqueness / checkpointing mechanism (which does not rely on the file path).
+  The purpose of this list was to allow us to emit a lot whenever a path was seen for the first time.
+  This removes the separate list and relies instead on the same mechanism as checkpointing. Now, a similar log is emitted
+  any time a file is found which is not currently checkpointed. Because the checkpointing mechanism does not maintain history
+  indefintiely, it is now possible that a log will be emitted for the same file path. This will happen when no file exists at
+  the path for a period of time.
+
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: []

pkg/stanza/fileconsumer/config.go

@@ -183,7 +183,6 @@ func (c Config) buildManager(logger *zap.SugaredLogger, emit emit.Callback, spli
 		maxBatches:        c.MaxBatches,
 		previousPollFiles: make([]*reader.Reader, 0, c.MaxConcurrentFiles/2),
 		knownFiles:        make([]*reader.Metadata, 0, 10*c.MaxConcurrentFiles),
-		seenPaths:         make(map[string]struct{}, 100),
 	}, nil
 }
 

pkg/stanza/fileconsumer/file.go

@@ -34,7 +34,6 @@ type Manager struct {
 
 	previousPollFiles []*reader.Reader
 	knownFiles        []*reader.Metadata
-	seenPaths         map[string]struct{}
 
 	currentFps []*fingerprint.Fingerprint
 }
@@ -178,14 +177,6 @@ func (m *Manager) consume(ctx context.Context, paths []string) {
 }
 
 func (m *Manager) makeFingerprint(path string) (*fingerprint.Fingerprint, *os.File) {
-	if _, ok := m.seenPaths[path]; !ok {
-		if m.readerFactory.FromBeginning {
-			m.Infow("Started watching file", "path", path)
-		} else {
-			m.Infow("Started watching file from end. To read preexisting logs, configure the argument 'start_at' to 'beginning'", "path", path)
-		}
-		m.seenPaths[path] = struct{}{}
-	}
 	file, err := os.Open(path) // #nosec - operator must read in files defined by user
 	if err != nil {
 		m.Errorw("Failed to open file", zap.Error(err))
@@ -274,5 +265,6 @@ func (m *Manager) newReader(file *os.File, fp *fingerprint.Fingerprint) (*reader
 	}
 
 	// If we don't match any previously known files, create a new reader from scratch
+	m.Infow("Started watching file", "path", file.Name())
 	return m.readerFactory.NewReader(file, fp)
 }